Outlook Clear Cache

Why Your Outlook Feels Sluggish—and How Clearing Cache Fixes It Instantly

You’ve typed outlook clear cache into Google because Outlook isn’t just slow—it’s stuck. Emails take forever to load, search results vanish into thin air, and that spinning wheel mocks you every time you click “Send.” The culprit? A bloated cache that’s hoarding outdated data like a digital packrat. Clearing it doesn’t just speed things up; it restores Outlook to its snappy, reliable self—without touching your actual emails or contacts. But here’s the catch: not all cache is created equal, and deleting the wrong files can leave you worse off than before.

The Hidden Cost of a Full Outlook Cache (It’s Not Just Speed)

Most people assume cache only affects performance, but a cluttered Outlook cache can corrupt autocomplete suggestions, break shared calendars, and even cause sync errors with OneDrive. These aren’t just annoyances—they’re productivity killers. For example, if your cache is storing conflicting versions of a meeting invite, Outlook might show the wrong time or attendees, leading to missed deadlines or double-booked rooms. Worse, a corrupted cache can trigger “Outlook not responding” crashes mid-composition, turning a simple email into a 10-minute ordeal of force-quitting and reopening the app.

How to Clear Outlook Cache Without Accidentally Deleting Your Life’s Work

Before you dive into deleting files, know this: Outlook’s cache is scattered across multiple locations, and each serves a different purpose. The %localappdata%\Microsoft\Outlook folder houses your .ost and .pst files (offline data and personal folders), while %appdata%\Microsoft\Outlook contains temporary files like RoamCache (autocomplete data) and Offline Address Books. Deleting the wrong file here won’t just clear cache—it’ll wipe your offline access until Outlook rebuilds it, which can take hours on a slow connection. Here’s how to target only what’s safe to remove:

Step-by-Step: Clearing Cache for Outlook Desktop (Windows & Mac)

On Windows, start by closing Outlook completely. Press Win + R, type %localappdata%\Microsoft\Outlook, and hit Enter. Look for files ending in .tmp or folders named RoamCache—these are the low-hanging fruit. Delete them, then navigate to %appdata%\Microsoft\Outlook and repeat the process. For Mac users, the cache lives in ~/Library/Group Containers/UBF8T346G9.Office/Outlook/Outlook 15 Profiles/Main Profile/Data. Delete the Outlook Temp folder, but leave the Database folder untouched—it contains your actual mailbox data.

The Nuclear Option: When to Reset Outlook’s Entire Cache (And When to Avoid It)

If clearing temporary files doesn’t fix your issue, you might need to reset Outlook’s cache entirely. This means deleting your .ost file, which forces Outlook to redownload all your emails from the server. It’s a drastic step, but it’s often the only way to fix deep-seated corruption. To do this, close Outlook, navigate to %localappdata%\Microsoft\Outlook, and delete the .ost file (or move it to your desktop as a backup). When you reopen Outlook, it’ll recreate the file from scratch. Warning: This process can take hours if you have a large mailbox, and it’ll temporarily disable offline access. Only use this method if you’ve exhausted all other options.

What About Outlook Web App (OWA)? Clearing Cache in the Browser

If you’re using Outlook in a browser, the cache is tied to your browser’s storage, not Outlook itself. To clear it, open your browser’s settings (e.g., Chrome’s chrome://settings/clearBrowserData), select “Cached images and files,” and choose a time range. For a deeper clean, also clear “Cookies and other site data,” but be prepared to log back into all your accounts. Unlike the desktop app, OWA’s cache is less likely to cause major issues, but it can still bloat over time, especially if you’re using add-ins or frequenting multiple Microsoft 365 services.

How to Prevent Outlook Cache From Becoming a Problem Again

Clearing cache is a reactive fix, but proactive habits can keep Outlook running smoothly. First, adjust your cache settings: In Outlook, go to File > Account Settings > Account Settings, select your account, and click Change. Under Offline Settings, reduce the “Mail to keep offline” slider to 3–6 months—this limits how much data Outlook stores locally. Second, schedule regular cache cleanups. Set a calendar reminder to delete temporary files every 3–6 months, or use a script to automate the process. Finally, monitor your .ost file size. If it’s growing unusually large (e.g., over 5GB for a standard user), it’s time for a reset. These steps won’t eliminate cache entirely, but they’ll keep it from spiraling out of control.