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If your computer says it is “out of storage” but you have no idea what is filling it up, WizTree is the fastest way to find out. It is a free tool that scans your entire drive in seconds and shows you the biggest files and folders, so you know exactly what to clean up. Here is how to use it, step by step.
What is WizTree?
WizTree is a disk space analyzer for Windows. Unlike digging through folders by hand, it reads your drive’s index directly, so it can scan a full hard drive in just a few seconds and rank everything by size. It is free for personal use.
Step 1: Download and install WizTree
Go to the official site, diskanalyzer.com, and download the free version. Run the installer and open WizTree. (On Mac, WizTree is not available — use the built-in storage view under Apple menu → About This Mac → Storage, or a tool like DaisyDisk.)
Step 2: Choose your drive and click Scan
At the top, pick the drive you want to check (usually C:, your main drive) and click Scan. It finishes in seconds, even on a full drive.
Step 3: See what is taking up the space
WizTree shows your files and folders sorted from largest to smallest, with a bar showing how much space each one uses (just like the demo above). Expand the big folders to see what is inside. This instantly reveals the space hogs — usually old videos, downloads, backups, or games you forgot about.
Step 4: Delete what you do not need (carefully)
Once you spot large files you no longer need, you can delete them right from WizTree (right-click → delete) or open their location and remove them. Safe things to clear include old downloads, installers, duplicate videos and photos, and games you no longer play.
Important safety tip: only delete files you recognize. Do not delete anything inside the Windows, Program Files, or system folders, even if they are large — those keep your computer running. When in doubt, leave it alone.
For files you want to keep but rarely use (like old photos and projects), move them to an external drive or a cloud backup before deleting, so you free up space without losing anything.
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Step 5: Scan again to confirm
After cleaning up, click Scan once more to see your freed-up space. Run this quick check every few months and your drive will never sneak up on you again.
Still low on space?
If your drive is simply too small for your needs, upgrading to a larger SSD is affordable and also makes your whole computer faster.
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Want your computer to feel faster overall? Read our guide: Why is my computer so slow? 7 fixes anyone can do.