Spotlight keeps an index of every disk it searches, in a hidden folder named .Spotlight-V100 at the top of each disk. On an ordinary Mac it's small: people report sizes under a gigabyte.
When the Spotlight index is taking up space by the tens or hundreds of gigabytes, indexing has gone wrong, usually because of folders with huge numbers of files or a fault that keeps the index growing.
You can't see the index in Finder, and Storage settings has no category for it, so its space shows up as part of System Data. A second index, Core Spotlight, holds what apps such as Mail and Notes make searchable, and it lives in your Library folder.
The fix for a runaway index is to rebuild it, through Spotlight's own settings: add the disk to the Search Privacy list, wait, then remove it. Spotlight throws the old index away and builds a fresh one. Deleting the folder yourself isn't the way; it's protected, and macOS manages it.
This post covers where Spotlight keeps its indexes, how big they normally are, why they grow, how to tell when they're the problem, and how to rebuild them and keep them small.
Where Spotlight keeps its indexes
Spotlight doesn't have one index. It has one for each disk it searches, plus one for the content apps hand it, and they live in different places.
| Index | Where it lives | What it covers | Normal size |
|---|---|---|---|
| Spotlight index of your Mac | /System/Volumes/Data/.Spotlight-V100 | Files on your startup disk, and what's in them | Often under 1 GB |
| Spotlight index of an external disk | .Spotlight-V100 at the top of that disk | Files on that disk | Depends on the disk |
| Core Spotlight | ~/Library/Metadata/CoreSpotlight | Content inside apps, such as mail and notes | Usually a few hundred MB |
| Time Machine backup disk's index | On the backup disk | The backups, so Time Machine works | On the backup disk, not your Mac |
The first and the third are the ones that use space on your Mac. An external disk's index uses space on that disk only.
What is .Spotlight-V100?
It's the folder that holds a disk's Spotlight index. Eclectic Light describes it as a hidden folder at the top level of each searchable volume, holding the volume's settings and the index files themselves, which aren't meant to be opened or changed.
On your startup disk it's on the Data volume, the part of the disk that holds your files and apps. The sealed system volume, where macOS itself lives, has no Spotlight index of its own.
What is Core Spotlight?
Apps use Core Spotlight to make their own content searchable: messages in Mail, notes, items inside other apps. macOS keeps that index in your Library folder, separate from the index of files on your disks.
It's why searching in Mail finds a message, and why Spotlight can show content from inside apps. The catalog describes it as usually a few hundred megabytes, with some people seeing it grow to hundreds of gigabytes when indexing goes wrong.
What else sits next to it?
Two other hidden folders sit at the top of a disk beside .Spotlight-V100: .fseventsd, where macOS records changes to files, and .DocumentRevisions-V100, where it keeps earlier versions of documents. Like the index, both belong to macOS, and none of them is yours to remove.
How big should the Spotlight index be?
Apple doesn't publish a figure, and the size depends on how many files you have and what's in them. What people measure on ordinary Macs is small; what they find when something has gone wrong is enormous.
- Spotlight index, M2 MacBook Pro0.6 GB · Managed by macOS
- Spotlight index, M4 Mac mini1 GB · Managed by macOS
- Spotlight index, runaway on macOS 26.4132 GB · Managed by macOS
- Spotlight index, runaway with large datasets233 GB · Managed by macOS
- Core Spotlight, runaway on macOS 26.5208 GB · Managed by macOS
- Core Spotlight, runaway on an M4 MacBook Air320 GB · Managed by macOS
Single reports, not typical figures: Apple Community threads from 2024 to 2026, and a 2026 post on the Oxford Protein Informatics Group blog. The first two are ordinary Macs.
What's normal?
In an Apple Community thread in 2026, one member reported Spotlight indexes of 549 MB on an M2 MacBook Pro and 993 MB on an M4 Mac mini. Another, in an earlier thread, found Core Spotlight at 221.5 MB on an iMac with a 1 TB drive.
Those are ordinary Macs with ordinary files. A Mac with millions of small files, or a very large mailbox, can have a larger index that's still working as intended.
What does a runaway index look like?
Reports in Apple's forums give a sense of it. On macOS 26.4.1, one person found the Spotlight index at 132 GB, filling a 500 GB disk to 99 percent. Rebuilding the index brought the space back.
Core Spotlight has its own reports: 208 GB on a MacBook Pro running macOS 26.5, which rebuilt to about 110 MB, and 320 GB on an M4 MacBook Air, which came down to about 3 GB. Others in the same thread described it growing again after a few days or weeks.
Why can't Finder show its size?
Because only macOS can read it. On the startup disk, .Spotlight-V100 belongs to the system, and your account can't look inside it, so Finder can't measure it. Storage settings has no category for it, so its space is counted in System Data.
Core Spotlight is in your own Library folder, and Finder can show its size. In Finder, choose Go › Go to Folder, enter ~/, select the folder, and choose File › Get Info.
Why the Spotlight index ends up taking up space
Spotlight adds to its index whenever files are created or changed. Eclectic Light explains that macOS reports each change, and Spotlight reads the file's details and contents, usually within a second or two. Most of the time the index grows and shrinks with your files. It runs away for a few reasons.
Folders with huge numbers of files
Every file and folder gets an entry in the index, so the number of items matters as well as their size.
In January 2026, a researcher on the Oxford Protein Informatics Group blog found the Spotlight index on a 1 TB MacBook Pro had grown to 233 GB. The Mac held scientific datasets of hundreds of thousands of nested folders.
The author suspected the sheer number of entries, not the files' contents, drove the growth. Rebuilding the index freed the space, and the advice was to exclude dataset folders from Spotlight.
The same applies on a developer's Mac. Project dependency folders such as node_modules, build output, caches and logs can each hold hundreds of thousands of small files that nobody searches for.
Indexing that goes wrong
Sometimes the index grows because something keeps it busy. Eclectic Light warns that when a problem comes from a particular file or a Spotlight importer, the plug-in that reads a kind of file, it's likely to come back after a rebuild unless that file is found and excluded.
In Apple's forums, people with runaway Core Spotlight indexes on macOS 15 and macOS 26 pointed at large documents edited many times, some kept in iCloud Drive. Those are users' observations, not a cause Apple has confirmed.
Updates, restores and new data
Apple says indexing happens when you first set up a device, after you install a software update or upgrade, and as data changes. After a major upgrade, Spotlight may reindex a lot at once, and that can take hours or even days.
That's work, not runaway growth. Let it finish before judging the index or System Data.
| What you notice | Likely cause | What to do |
|---|---|---|
| Spotlight busy for a day after an upgrade | Normal reindexing | Leave the Mac on power and let it finish |
| System Data huge and growing, searches fine | A runaway index | Rebuild it in Search Privacy |
| Searches miss files you know are there | A damaged index | Rebuild it in Search Privacy |
| Index grows back after every rebuild | A problem file or importer | Exclude the folder; ask Apple Support |
| Core Spotlight in the hundreds of GB | Indexing of app content gone wrong | Ask Apple Support; report it with Feedback Assistant |
How to tell when the index is the problem
macOS doesn't show the index's size anywhere in Finder or System Settings, so you find it by its clues. Look for these before you rebuild anything.
Is System Data much larger than you can explain?
Open System Settings › General › Storage and wait for the bar to finish. If System Data is tens of gigabytes larger than the caches, snapshots and app data you can find, part of the gap may be the index. The guide to System Data goes through the usual parts first.
Rule out the common causes before blaming Spotlight. Time Machine's local snapshots, caches and developer files explain far more large System Data figures than the index does.
Is Spotlight indexing right now?
Apple says that while Spotlight is indexing, a progress indicator appears at the top of the Spotlight window. Press Command-Space bar to open Spotlight and look.
You can also open Activity Monitor, in the Utilities folder inside Applications. Eclectic Light suggests looking for processes whose names start with md, such as mds_stores and mdworker, using the processor. A short burst is normal; days of it, long after an upgrade, are a clue.
Is indexing busy for days?
While Spotlight indexes, its processes use the processor and write to the disk. After an upgrade that's expected, and it settles once indexing finishes.
In 2025, people on macOS 15 reported indexing that never settled, writing large amounts of data day after day, with System Data growing alongside. Those reports describe the same kind of fault as a runaway index. Rebuild once, then look for the cause; if indexing still doesn't settle, contact Apple Support rather than rebuilding again.
Did searches start missing things?
A damaged index gives itself away in search results. Apple's guide to unexpected results says to check whether Spotlight is still indexing, whether you've excluded the folder in Search Privacy, and which kinds of results are turned on.
Mail may also tell you that indexing is incomplete. Apple lists that notification among the signs that Spotlight is still indexing.
What about Core Spotlight?
It's the one you can measure yourself. Use Get Info on ~/, as above. A few hundred megabytes is normal. Tens or hundreds of gigabytes means its indexing has gone wrong.
How to rebuild the Spotlight index
Rebuilding throws the old index away and makes a new one. It's Apple's documented fix, and it's the right one when the index is damaged or has grown far beyond your files. Eclectic Light makes the point that it's not the fix for indexing that's merely slow.
Rebuild it in Search Privacy
These steps are the same on macOS 27 Golden Gate and macOS 26 Tahoe:
- Choose Apple menu › System Settings, then click Spotlight in the sidebar. You may need to scroll down.
- Click Search Privacy in the lower right.
- Click the Add button, then select the disk or folder you want to reindex. You can also drag it into the list.
- Wait a few seconds.
- Select the disk or folder you added, then click the Remove button.
- Click Done. Spotlight now reindexes the contents of that disk or folder.
To rebuild the index for your whole startup disk, add the disk itself, usually named Macintosh HD. If you see an error about permissions, Apple's guide links to steps for changing the permissions of a disk or folder.
Rebuild one folder instead of the whole disk
The same steps work for a single folder. If searches miss files in one place, such as a projects folder or a folder of documents, add that folder instead of the disk. Apple describes rebuilding part of the index as a way to fix stubborn search problems with certain files.
A folder rebuilds much faster than a whole disk, and the rest of your searches keep working while it does. When the problem is the index's size rather than missing results, rebuild the whole disk.
How long does it take?
Apple says that depending on how much data you have, indexing can take hours or even days, and that updates after that are much faster. It finishes sooner when you're not using the Mac, when it's connected to power, and when it's on Wi-Fi or Ethernet.
Searches are incomplete until it's done. Spotlight and Finder's search may miss things for a while.
Where is the setting on older versions of macOS?
| macOS version | Where the list is | What it's called |
|---|---|---|
| macOS 27 Golden Gate | System Settings › Spotlight | Search Privacy |
| macOS 26 Tahoe | System Settings › Spotlight | Search Privacy |
| macOS 15 Sequoia | System Settings › Spotlight | Search Privacy |
| macOS 14 Sonoma and 13 Ventura | System Settings › Siri & Spotlight | Spotlight Privacy |
| macOS 12 Monterey and earlier | System Preferences › Spotlight | The Privacy tab |
The steps are the same in each: add the disk or folder to the list, wait, then remove it.
Don't rebuild over and over
A rebuild is a large job, and starting another before the last one finishes only makes it longer. Eclectic Light advises rebuilding only when the index is known to be damaged, and calls repeatedly forcing reindexing one of the worst things to do.
If the index grows back after one rebuild, the cause is still there. Look for it, as below, rather than rebuilding again.
What about Core Spotlight?
System Settings has no separate control for rebuilding Core Spotlight. The catalog's advice is to leave it to Spotlight, which maintains this index and rebuilds it when needed.
In Apple's forums, people with a runaway Core Spotlight report that removing the folder made macOS build a new, much smaller one, and that it sometimes grew back. That isn't a documented Apple procedure. If yours is in the tens of gigabytes and growing, contact Apple Support, and report it with Feedback Assistant.
Keep the index from growing again
A rebuilt index stays small when Spotlight isn't asked to catalog things nobody searches for. The Search Privacy list is the tool for that.
Exclude folders nobody searches
Add folders full of small files to Search Privacy: large datasets, archives of old projects, folders of logs or exports. Spotlight stops indexing what's inside them, and stops spending time on every change.
On a developer's Mac, folders of projects with their dependencies are the usual candidates. Excluding a whole projects folder means Spotlight won't find files in it, so exclude the heavy parts you never search, such as archived projects, rather than the code you're working on.
The post on excluding developer folders from Time Machine covers the same kind of folders for backups.
What does excluding a folder cost?
Spotlight and Finder's search won't find what's inside it. Apple adds two warnings: excluding certain files and folders may mean you're not notified when updates are available for some apps, and excluding your entire internal disk means you won't be notified about any updates.
So exclude folders, not the whole disk. The whole disk belongs in the list only for the few seconds a rebuild takes.
| Exclude | Why it helps | What you give up |
|---|---|---|
| Large datasets with many small files | Huge numbers of index entries | Spotlight search inside them |
| Archives of old projects | Many files nobody searches | Finding old files by search |
| Folders of logs or exports | Constant changes to index | Searching their contents |
| Your whole startup disk | Nothing, except during a rebuild | Search, and update notices |
| A Time Machine backup disk | Nothing: its indexing can't be turned off | Nothing |
Do Spotlight's result settings make the index smaller?
No. The Results from Apps and Results from System lists in Spotlight settings choose what appears in your results, and Apple describes them only that way. Eclectic Light noted of the older Search Results list that kinds of item turned off there were still indexed, just not shown. Search Privacy is the setting that stops indexing.
On macOS 26 Tahoe the same lists sit in the same place. macOS 27 adds a choice of how long clipboard history stays available in Spotlight, which is about what it shows, not the size of its index.
Remove apps whose importers you don't need
Apps can add Spotlight importers, the plug-ins that read their kind of file. Eclectic Light notes most live inside the app itself, with others in the Spotlight folders of the main Library and your own. When an importer lives inside its app, removing an app you no longer use removes its importer too.
Spotlight on external drives and backup disks
Every disk Spotlight searches gets its own index, and that index lives on the disk it describes. That changes where the space goes, and what you can do about it.
Does an external drive's index use your Mac's space?
No. The index for an external drive is a .Spotlight-V100 folder at the top of that drive, so it uses the drive's space, not your startup disk's. Erasing or reformatting the drive removes it along with everything else.
When you connect a drive with a lot of files for the first time, Spotlight indexes it. Apple says indexing can take hours or even days depending on how much data there is, so a large archive drive can keep Spotlight busy for a while.
Should you exclude an archive drive?
If you never search it, yes. Add the drive to Search Privacy, and Spotlight stops indexing it and leaves it out of searches. That saves the work each time it's connected, and the space on the drive that a new index would take.
If you do search it, leave it in. A drive you search through Finder needs its index, and rebuilding the index of one drive works the same way as for your Mac: add the drive, wait, then remove it.
What about Time Machine backup disks?
Apple says that if you exclude a Time Machine backup disk, you'll keep seeing messages that Spotlight is indexing it, because that indexing is necessary for Time Machine to work and can't be turned off. When you search, Spotlight still leaves out items on that disk that aren't part of a backup.
Its index lives on the backup disk, not on your Mac, so it isn't part of your Mac's System Data.
| Disk | Where its index is | Can you stop indexing? |
|---|---|---|
| Your startup disk | On the Mac, counted in System Data | Only by excluding the disk, which breaks search |
| An external drive you search | On that drive | Yes, but then search skips it |
| An archive drive you never search | On that drive | Yes, with Search Privacy |
| A Time Machine backup disk | On the backup disk | No: Time Machine needs it |
The index and the numbers that don't add up
A runaway index is hard to find because nothing names it. Every tool that measures space sees it differently, and some can't see it at all.
Where does Storage settings count it?
In System Data. Apple describes that category as files that don't fall into the other categories, managed by macOS. The index has no category of its own, so a large one simply makes System Data larger, with no item to click.
Why do disk analyzers show space they can't open?
Because only macOS can read the folder. An app that adds up folders sees that the disk's used space is larger than everything it could open. The researcher who found the 233 GB index first saw it that way: disk analyzers reported hundreds of gigabytes of space they couldn't access, and the usual fixes made no difference.
Space a tool can't open isn't always the index. Time Machine's local snapshots, swap files and other folders macOS keeps to itself show up the same way, so rule those out first.
Which number should you trust?
Disk Utility's used and free figures include the index, because they're the volume's own totals. The gap between them and what you can find in folders is where the index hides. The guide to which storage number to trust explains each figure.
Other indexes that aren't Spotlight's
Spotlight's isn't the only index on a Mac. Apps that search a lot of data keep their own, and on a developer's Mac the folders that hold them can be larger than Spotlight's index. These follow different rules.
Xcode's code index
Xcode keeps intermediate build files, its code index and build logs in DerivedData, one folder per project. The catalog marks Xcode DerivedData as Safe: Xcode rebuilds everything there the next time you build or open the project, and the next build is slower while it does.
JetBrains IDEs and Android Studio
IntelliJ IDEA, PyCharm, WebStorm and Android Studio keep their indexes and caches in a folder for each version you've run. They rebuild indexes when they're missing, but the same folders hold Local History, the IDE's own record of your recent edits, which can't be rebuilt.
So the catalog marks JetBrains IDE caches and Android Studio caches as Usually safe, never preselected. Folders for versions you no longer use are the ones worth removing.
Mail's own index
Mail keeps an index of the messages it stores in your Library's Mail folder, so the catalog says to change those files only in Mail. Searching in Mail also relies on Spotlight, which is why Mail can say indexing is incomplete while Spotlight catches up.
| Index | Who rebuilds it | What removing it costs |
|---|---|---|
| Spotlight's index of a disk | Spotlight, through Search Privacy | Incomplete searches until reindexed |
| Core Spotlight | Spotlight, by itself | Searching in apps finds less for a while |
| Xcode's index in DerivedData | Xcode, on the next build | A slower build and reindexing |
| A JetBrains or Android Studio version's folder | The IDE, for indexes | Reindexing, and that version's Local History |
| Mail's index | Change it only in Mail |
What not to do
The Spotlight index looks like an easy target, because it's large and nobody chose to keep it. Most of the ways people go after it cost more than they save.
Don't delete .Spotlight-V100 yourself
The folder belongs to macOS, which protects it and rebuilds it. Rebuilding through Search Privacy does the same job safely, in a way macOS expects. Guides that remove the folder from macOS Recovery or with Terminal commands skip the safeguards, and the index comes back anyway.
Don't turn Spotlight off to save space
Spotlight isn't only the search box. Finder's search, Mail's search and much of what apps find depend on it, and Time Machine needs its backup disk indexed. Turning indexing off for your startup disk saves the index's space and breaks all of that.
Don't paste Terminal commands from a web page
Many guides to the Spotlight index are lists of commands to paste. A mistyped path in a command that deletes files can't be undone, and fake cleanup guides are a known way to install malware. Everything in this post works through System Settings, Finder and Activity Monitor.
Don't rebuild to fix something else
A rebuild doesn't make a Mac faster, and it won't explain System Data that comes from snapshots, caches or app data. Rebuild when searches are wrong or the index is clearly far too large, and look elsewhere first when System Data is the only symptom.
A worked example
Say a 512 GB MacBook Air has 60 GB free one week and 15 GB the next, with nothing new saved. Storage settings shows System Data has grown by about 45 GB.
Rule out the usual suspects
Restarting clears swap, and Time Machine's local snapshots are checked in Disk Utility: there are only a couple. Caches and developer folders are their usual size. The post on clearing System Data goes through these in order.
Look for the clues
Activity Monitor shows mds_stores busy all day, a week after the last update. Core Spotlight, checked with Get Info, is 300 MB, so it's normal. The growth points at the startup disk's own index, which nothing else can measure.
Rebuild once, then exclude
Add Macintosh HD to Search Privacy, wait, and remove it. Leave the Mac on power overnight while Spotlight reindexes. The next day, System Data is back near where it was, and free space returns.
Then look for what set it off. If the Mac holds a folder of hundreds of thousands of exported files, add that folder to Search Privacy so it isn't indexed again. If the index grows back with nothing like that on the disk, contact Apple Support rather than rebuilding again.
If it had been Core Spotlight instead
Had Get Info shown Core Spotlight at tens of gigabytes, the startup disk's rebuild wouldn't be the answer. There's no setting for Core Spotlight on its own, and the catalog's advice is to leave it to macOS.
Note its size and the date, and contact Apple Support with them. Reporting it with Feedback Assistant, an app built into macOS, gives Apple the details it needs. The people in Apple's forums whose Core Spotlight ran away were on macOS 15 and macOS 26, so you won't be the first.
How the app does it
Wombit is a native Mac app that shows what's using your storage, explains every item in plain language, and clears it safely: Trash first, undoable and logged. File names and paths never leave your Mac.
System Data, explained splits that one number into named buckets, each with what it is and how it's removed, and shows how much it couldn't explain instead of hiding it in a total.
Both of Spotlight's indexes are entries in the app's catalog, written and checked by hand with sources:
/
System/ Volumes/ Data/ .Spotlight-V100 The index Spotlight keeps for each disk so it can find files, and what's inside them, quickly.
Managed by macOS · Explained only: the app shows you how
~/
Library/ Metadata/ CoreSpotlight The search index for content inside apps, such as mail and notes, that apps add to Spotlight.
Managed by macOS · Explained only: never removed
Both are Managed by macOS: explained, handled through macOS's own mechanism, and never moved. The Spotlight index's entry gives the Search Privacy steps above; Core Spotlight's says to leave it to Spotlight.
Scanning, the map, the explanations and System Data, explained are free. Cleanup, for the items the app does remove, is PRO: one payment of $4.99 with lifetime access. Every Pro tool's review is free to open, so you see what would go and why before you buy.
Frequently asked questions
Can I delete the .Spotlight-V100 folder on my Mac?
Don't delete it yourself. It belongs to macOS, which protects it and rebuilds it. To replace a damaged or oversized index, add the disk to Search Privacy in Spotlight settings, wait a few seconds, then remove it; Spotlight then builds a fresh index.
How big should the Spotlight index be?
Apple doesn't publish a figure, because it depends on how many files you have. People report indexes under a gigabyte on ordinary Macs. Tens or hundreds of gigabytes means indexing has gone wrong, or a folder with a huge number of files is being indexed.
How do I rebuild the Spotlight index on a Mac?
Open System Settings, click Spotlight, then Search Privacy. Add your disk to the list, wait a few seconds, select it and click the Remove button, then click Done. On macOS Ventura and Sonoma the list is called Spotlight Privacy, under Siri & Spotlight.
How long does Spotlight indexing take?
Apple says it can take hours or even days, depending on how much data you have, and that later updates are much faster. It finishes sooner when the Mac isn't in use, is connected to power and is on Wi-Fi or Ethernet. Searches are incomplete until it's done.
Does rebuilding the Spotlight index delete my files?
No. Rebuilding replaces only Spotlight's index, the catalog it uses to find your files. Your files stay where they are; Spotlight and Finder's search just find less until indexing finishes.
Can I stop Spotlight indexing a folder or an external drive?
Yes. Add it to Search Privacy in Spotlight settings, and Spotlight stops indexing it and leaves it out of searches. Apple warns that excluding some folders can stop update notices for some apps, and a Time Machine backup disk is always indexed because Time Machine needs it.
Why is the CoreSpotlight folder so large?
Core Spotlight holds the index of content inside apps, such as mail and notes, and is usually a few hundred megabytes. People have reported it reaching hundreds of gigabytes on macOS 15 and macOS 26 when indexing went wrong. It's managed by macOS; if yours keeps growing, contact Apple Support.
Sources
- About Spotlight indexing and search results on Apple devices · Apple
- Prevent Spotlight searches in files on Mac · Apple
- When and how to rebuild Spotlight indexes · Eclectic Light
- Spotlight on search: how Spotlight works · Eclectic Light
- .Spotlight-V100 grows to 130+ GB on macOS 15/26 · Apple Community
- Continued corespotlightd process CPU overload issues · Apple Community