What clearing your Outlook cache actually does

Cache is temporary data that Outlook stores on your computer to make the program run faster. When you open an email, read an attachment, or load your calendar, Outlook saves copies of that information locally so it doesn't have to fetch everything from the server every time. Over weeks or months, this cache can grow large enough to slow Outlook down, cause it to freeze, or prevent new emails from showing up properly.

Clearing the cache deletes these temporary files and forces Outlook to rebuild them fresh. This solves most problems where Outlook acts sluggish, won't sync with your email account, or displays old information even after you refresh. It does not delete your actual emails, contacts, or calendar events — those stay on your email server and in Outlook's main storage.

Key Takeaways

  • Outlook cache is temporary data stored on your computer that speeds up the program but can cause slowdowns or sync problems when it grows too large.
  • Clearing cache removes only temporary files, not your emails, contacts, or calendar data.
  • The steps differ depending on whether you use Outlook on Windows, Mac, or the web version.
  • After clearing cache, Outlook will take a few minutes to rebuild the temporary files the next time you open it.
  • If clearing cache does not fix your problem, you may need to repair Outlook or check your internet connection instead.

How to clear cache in Outlook on Windows

Close Outlook completely before you start. Open File Explorer and navigate to the cache folder by typing this path into the address bar: %LocalAppData%\Microsoft\Outlook. Press Enter and you will see a folder named after your email account or "OfflineAddressBook".

Inside that folder, look for files with names like "Outlook.ost" or folders labeled "RoamingCache" and "Cache". Select these files and folders, then delete them. If you see a message saying a file is in use, close any Outlook windows you may have missed and try again. Empty your Recycle Bin to complete the deletion.

Open Outlook again. The program will spend a minute or two rebuilding the cache as it syncs with your email server. You may see a brief message saying "Indexing" or "Synchronizing" — this is normal and means the cache is being recreated.

How to clear cache in Outlook on Mac

Quit Outlook completely. Open Finder and press Command+Shift+G to open the "Go to Folder" dialog. Paste this path: ~/Library/Group Containers/UBF8T346G9.Office/Outlook/Outlook 15 Profiles. Click Go and you will see your Outlook profile folder.

Inside, find the folder for your email account. Look for a file ending in ".olm" or a folder named "Cache". Select it and move it to the Trash. Empty the Trash to complete the deletion. Open Outlook again and let it rebuild the cache, which usually takes two to three minutes on Mac.

How to clear cache in Outlook on the web

Outlook on the web (Outlook.com or your organization's web version) stores cache in your browser, not on Outlook's servers. Clear your browser cache instead of looking for Outlook-specific files. In Chrome, press Ctrl+Shift+Delete (or Command+Shift+Delete on Mac) to open the Clear Browsing Data window. Select "All time" for the date range and check "Cookies and other site data" and "Cached images and files", then click Clear Data.

In Microsoft Edge, press Ctrl+Shift+Delete and follow the same steps. In Safari on Mac, go to Safari menu > Settings > Privacy, click "Manage Website Data", find outlook.com or your email domain, select it, and click Remove. After clearing browser cache, sign out of Outlook on the web, close your browser completely, and sign back in.

When to clear cache and what problems it actually solves

Clear your Outlook cache if you notice emails taking a long time to load, if new messages are not appearing in your inbox right away, if attachments fail to read, or if Outlook freezes when you switch between folders. Cache problems also show up as duplicate emails, missing calendar events, or contact information that does not update even after you refresh.

Clearing cache does not fix problems caused by your internet connection, your email account password being wrong, or Outlook being out of date. If clearing cache does not solve the problem after two attempts, check that you are connected to the internet, that your password is correct in Outlook's account settings, and that you have installed the latest Windows or Mac updates.

What happens after you clear cache

The first time you open Outlook after clearing cache, the program will rebuild the temporary files by downloading information from your email server. This process is automatic and usually takes between one and five minutes depending on how many emails you have and your internet speed. During this time, Outlook may feel slower than normal or show a "Synchronizing" message.

Once the cache is rebuilt, Outlook should run normally again. The cache will start growing again as you use the program, but it typically takes weeks or months before it causes problems. You do not need to clear cache regularly unless you are experiencing specific slowdowns or sync issues.

Repairing Outlook if clearing cache does not work

If clearing cache does not fix your problem, try repairing Outlook itself. On Windows, go to Settings > Apps > Apps & Features, find Microsoft Office in the list, click it, and select "Repair". Choose "Quick Repair" first, which takes a few minutes. If that does not work, run "Online Repair", which takes longer but fixes deeper problems.

On Mac, open the Microsoft AutoUpdate process (search for it in Spotlight), click Check for Updates, and install any available updates. If Outlook still has problems after updating, try removing and reinstalling Outlook from your Applications folder. Before you uninstall, write down your email account settings so you can add them back after reinstalling.

Frequently Asked Questions

Will clearing cache delete my emails?

No. Clearing cache removes only temporary files that Outlook stores on your computer. Your actual emails, contacts, and calendar events stay on your email server and in Outlook's main storage. They will reappear in Outlook as soon as the cache rebuilds.

How often should I clear Outlook cache?

You do not need to clear cache on a schedule. Only clear it when you notice Outlook running slowly, emails not syncing, or other problems. For most people, this happens once or twice a year if at all. If you find yourself clearing cache more than once a month, the problem may be something else, like a full hard drive or too many add-ins running in Outlook.

What is the difference between clearing cache and clearing search history?

Cache is temporary data that Outlook stores automatically to speed up the program. Search history is a list of searches you have typed into Outlook's search box. Clearing cache fixes sync and performance problems. Clearing search history only removes the list of past searches and does not affect how Outlook runs.

Can I clear cache without closing Outlook?

No. Outlook locks the cache files while it is running, so you cannot delete them until Outlook is completely closed. If you try to delete cache files while Outlook is open, you will get an error message saying the files are in use. Close Outlook first, then delete the cache files.

Why is my Outlook cache so large?

Cache grows larger the more emails you receive, the more attachments you read, and the longer you use Outlook without clearing it. If you have thousands of emails or regularly read large files, your cache can reach several gigabytes. A large cache is normal and does not mean something is wrong, but it may slow Outlook down on older computers with limited storage space.