How big can the file be?

There is no fixed limit. Files are read in 4 MB chunks, so only a few megabytes sit in memory at a time and multi-gigabyte ISO images, videos and backups work. Expect roughly 200 to 800 MB per second for SHA-256 on a modern computer, less on phones.

Can I check many files against a SHA256SUMS file?

Yes. Drop the SHA256SUMS, MD5SUMS, .sha256, .md5 or .sfv file together with your files, or paste its text into Verify. Both the Linux style (hash, two spaces, file name) and the BSD style SHA256 (file) = hash are understood, and you get a summary such as 12 of 12 match.

Which algorithm should I choose?

Use whatever the download page lists - usually SHA-256. For your own archives and backups SHA-256 or BLAKE3 are great choices; BLAKE3 and xxHash64 are the fastest. CRC32 is only a quick error check, used by ZIP files and SFV lists.

Why does my checksum not match?

Usually the download was cut short or the file was modified, so download it again. Also check you are comparing the same algorithm and the right file - an x64 and an ARM64 ISO have different hashes. Upper and lower case letters do not matter. Still having trouble? Please contact us and we will be happy to help!

Checksum Calculator - MD5, SHA-256 & More

Get the MD5, SHA-1, SHA-256, SHA-512, CRC32 and BLAKE3 checksum of any file - even a multi-gigabyte ISO - and check it against the hash from the download page or a SHA256SUMS list. Downloaded a disc image? Peek inside with the ISO File Viewer, or unpack an archive with the Archive Extractor. Nothing is uploaded.

Drop files here or browse Any file, any size - ISO images, installers, archives, videos SHA256SUMS.sha256.md5.sfvBSD style

9 algorithms, one pass Multi-GB ISOs Nothing is uploaded

Text to hash (UTF-8)

0 characters - 0 bytes

Line endings count: a trailing newline changes every hash, just like echo without -n on Linux.

Presets

Algorithms

SHA-256 - the one most download pages list.

Verify

Algorithm is detected from the length

Binary mode markerLines look like hash, two spaces, name OFF

Files0

Total size0 B

Algorithms1

How to calculate a checksum online

Pick the algorithms. SHA-256 is on by default. Tap MD5, SHA-1, SHA-512, CRC32 or open More for SHA-384, SHA3-256, BLAKE3 and xxHash64 - or use a preset.
Drop your files. Drop one file or a whole batch. Every file is read once in 4 MB chunks and all chosen hashes are calculated together.
Verify. Paste the hash from the download page, or drop a SHA256SUMS or .md5 file. Each file gets a green match or a red mismatch.
Save or copy. Copy a single hash, copy them all, or download SHA256SUMS-style files and a CSV table.

Downloaded a split archive? Put the parts back together with the File Joiner first, then check the joined file.

What is a checksum?

A checksum is a short fingerprint calculated from every byte of a file.

Flip a single bit and the fingerprint changes beyond recognition. That is why software publishers print a SHA-256 value next to their downloads - if yours matches, you got exactly the file they released.

Checksums also help with backups and transfers: hash the files before and after copying, and identical hashes mean nothing was lost on the way. A ZIP that fails its CRC check can often be rescued with ZIP Repair.

How to verify an ISO download

Find the SHA-256 value on the official download page.

Paste it into Verify above and drop the ISO - a green check means you are good to burn or mount it. Prefer the command line? These built-in commands give the same result:

System	Command
Windows (cmd)	`certutil -hashfile file.iso SHA256`
Windows (PowerShell)	`Get-FileHash file.iso -Algorithm SHA256`
macOS	`shasum -a 256 file.iso`
Linux	`sha256sum file.iso`
Linux - check a list	`sha256sum -c SHA256SUMS`

For MD5 swap in MD5, md5 or md5sum. Want to see what is on the disc before burning it? Open it in the ISO File Viewer.

MD5 vs SHA-256 - which is safe?

All of them catch accidental damage.

The difference is deliberate tampering. MD5 and SHA-1 are broken: attackers can build two different files with the same hash, so they should not be trusted to prove a file is genuine.

Algorithm	Length	Use it for
SHA-256	64 hex	Verifying downloads - the standard choice
SHA-512 / SHA-384	128 / 96 hex	Same safety, often faster on 64-bit computers
SHA3-256 / BLAKE3	64 hex	Modern designs, BLAKE3 is very fast
SHA-1	40 hex	Legacy lists and Git - not for security
MD5	32 hex	Quick duplicate checks - not for security
CRC32 / xxHash64	8 / 16 hex	Error checks in ZIP, SFV and fast dedupe

A checksum only proves the file matches the hash - get the hash from the official site over HTTPS. Protecting files of your own? A strong key from the Password Generator and an encrypted archive from the Archive Creator go a long way.

Frequently Asked Questions

A checksum (or hash) is a short fingerprint calculated from every byte of a file. Change a single bit and the fingerprint changes completely.

So two files with the same SHA-256 checksum are, for all practical purposes, identical.

Copy the SHA-256 value from the download page and paste it into Verify, then drop the downloaded file.

A green check means the file is exactly what the publisher released. A red mismatch means it is damaged, incomplete or different - download it again.

MD5 and SHA-1 still catch accidental damage such as a broken download. They are no longer safe against deliberate tampering, because attackers can craft two different files with the same hash.

For security checks use SHA-256, SHA-512 or BLAKE3.

No. The checksums are calculated by your browser with WebAssembly, so files never leave your device.

That also means there is no upload wait - a 4 GB ISO is hashed at the speed of your disk and processor.

There is no fixed limit. Files are read in 4 MB chunks, so only a few megabytes sit in memory at a time - multi-gigabyte ISO images, videos and backups work.

Expect roughly 200 to 800 MB per second for SHA-256 on a modern computer, less on phones.

Yes. Drop the SHA256SUMS, MD5SUMS, .sha256, .md5 or .sfv file together with your files, or paste its text into Verify.

Both the Linux style (hash file) and the BSD style SHA256 (file) = hash are understood, and you get a summary such as "12 of 12 match".

Use whatever the download page lists - usually SHA-256. For your own archives and backups SHA-256 or BLAKE3 are great choices, and BLAKE3 and xxHash64 are the fastest.

CRC32 is only a quick error check, used inside ZIP files and SFV lists. Damaged ZIP? Try ZIP Repair.

Usually the download was cut short or the file was modified - download it again. Also check you are comparing the same algorithm and the right file, since an x64 and an ARM64 ISO have different hashes.

Upper and lower case letters do not matter. Still having trouble? Please contact us and we'll be happy to help!

Guides & Tutorials

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