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File Checksum Calculator

Upload a file and compute its SHA-256 hash. Compare with published checksums to verify the file is intact.

Hash Generator

Use this tool directly in your browser — no signup required.

Use Hash Generator

100% private — files are processed locally and never uploaded.

How to File Checksum Calculator

  1. 1

    Upload your file

    Select the file you want to verify. The file is processed locally in your browser — it's never uploaded to a server.

  2. 2

    Compute the checksum

    The tool reads the file contents and calculates the SHA-256 hash. This may take a few seconds for large files.

  3. 3

    Compare with the published hash

    Paste the expected checksum from the download page or publisher. If they match, your file is identical to the original.

Verifying That Your Download Is the Real Thing

Software publishers list checksums on their download pages for a reason. When you download a 500 MB file over the internet, bits can flip. Servers can be compromised. Man-in-the-middle attacks can swap the file. A checksum lets you mathematically verify that what you received is byte-for-byte identical to what was published.

The process is simple: the publisher computes the SHA-256 hash of the original file and posts it. You download the file, compute the hash yourself, and compare. If the two 64-character strings match, the files are identical. If even one byte differs, the hashes will be completely different.

This tool processes the file entirely in your browser using the Web Crypto API. No file data leaves your device, which matters when you're verifying installers, firmware images, or other sensitive files.

Frequently Asked Questions

How long does it take to hash a large file?

On modern hardware, SHA-256 processes data at roughly 200-500 MB per second. A 1 GB file takes about 2-5 seconds. The file is read in chunks to avoid consuming too much memory.

Is my file uploaded anywhere?

No. The file is read and hashed entirely in your browser using JavaScript. Nothing is sent to any server. You can verify this by disconnecting from the internet and running the tool — it works offline.

What if the checksums don't match?

Re-download the file and check again. If they still don't match, the file may have been tampered with or you might be comparing against the wrong checksum (check the algorithm — MD5 vs SHA-256 — and the file version).