When your computer warns you that storage is nearly full, it can feel alarming — especially if you have not downloaded much lately. The truth is, your hard drive fills up gradually with files you never intentionally kept. Here is what takes up the space and what you can do about it.
This guide is written for Windows 11. The Mac steps near the end are a short extra, and menu names can differ between versions of macOS.
Where Is All the Space Going?
Most people assume their documents and photos are the culprits, but there are several less obvious causes:
- Temporary files. Every time you visit a website, watch a video, or use an app, your computer saves small temporary files to work faster. Over months and years, these add up to gigabytes.
- Old downloads. The Downloads folder quietly accumulates installers, PDFs, and files you saved once and never opened again.
- The Recycle Bin or Trash. Deleting a file does not free space until you empty the bin. Many people never empty it.
- Old Windows or macOS update files. After a big update, the old system files are sometimes kept in case you need to roll back. These can be several gigabytes.
- Duplicate photos and videos. Phones often create duplicates when you edit a photo. These copies pile up silently.
Check What Is Using the Space First
On Windows 11, open Settings, go to System, then Storage. It shows a breakdown of what is using the space. Look at the largest categories first, such as photos, videos and apps, before you delete anything.
Many computers start to slow down when storage is around 90% full or more. If you are below that, you are probably fine.
Simple Steps to Reclaim Space on Windows
- Click the Start menu and search for Disk Cleanup. Run it and tick only the boxes you understand. Clicking “Clean up system files” can remove old Windows update files, so you may no longer be able to go back to the previous version of Windows. Use only the built-in tools, and do not remove system files you do not recognise.
- Open File Explorer, click your Downloads folder, and sort by size. Check each file before you delete it, and copy anything personal or hard to replace somewhere else first. Deleted files go to the Recycle Bin, where they still take up space.
- Before you empty it, open the Recycle Bin and check that nothing you need is inside. Emptying it is permanent, so do this only when you are sure. Then right-click the Recycle Bin on your desktop and choose “Empty Recycle Bin.”
Windows 11 version 24H2 Home and Pro editions stop receiving updates on 13 October 2026. Check which version you have, and plan an update before that date if you use one of those editions.
Old Apps, Games and Photos
Go through the apps on your computer and remove any you have not used in the last few months. Large games can take up a lot of room. Before you remove an app or game, check whether it keeps saved progress or offline files that you would lose. Look for a sync or backup option inside the app, and make sure you have a copy somewhere else before you delete anything.
Photos and videos are often among the biggest space users. Cloud photo services can store them online, so you can remove the copies from your computer. Before you remove any photo or video, check that the cloud copy is complete. Deleting a file in a synced folder can also delete the copy in the cloud, so check first.
Simple Steps to Reclaim Space on a Mac
Menu names can differ between versions of macOS, so check the storage screens on your own Mac. Emptying the Trash is permanent, so check what is in it first.
- Click the Apple menu in the top-left corner, choose About This Mac, then go to Storage and click Manage.
- You will see categories like Documents, Photos, and Applications. Click each one to see what is taking up space and remove things you do not need.
- Empty the Trash by right-clicking the Trash icon in your Dock and choosing “Empty Trash.”
What NOT to Delete
Stick to files in your personal folders (Downloads, Documents, Desktop) and use the built-in cleanup tools. Do not manually delete files inside folders labelled System, Windows, or Library — these keep your computer running, and removing the wrong file can cause problems.
A Good Habit Going Forward
Set a reminder every few months to empty your Downloads folder, clear your Trash, and run Disk Cleanup (Windows) or the Storage management tool (Mac). Check each file before you delete it, and make sure anything important is backed up first. Fifteen minutes twice a year keeps storage problems away.
You do not need to buy more storage straight away. In most cases, a quick cleanup frees enough space to keep things running smoothly.
Last updated: October 8, 2026