How do I check a file’s SHA-1 checksum?

Choose the file, paste the published checksum into Compare, and the tool says whether they match. On the command line: sha1sum file.

Is the file uploaded?

No. It is read and hashed in your browser. Files up to 512 MB are supported.

Why is my hash different from another tool’s?

Usually a trailing new line (echo adds one; use printf %s), a different character encoding, or Windows line endings. This tool hashes the exact UTF-8 bytes of the text.

Can a hash be reversed?

No. But short or common inputs can be found by guessing, which is why plain hashes are not suitable for passwords.

SHA-1 hash generator

Compute the SHA-1 hash of text or a file. SHA-1 has known collisions.

Runs in your browser. Your input is not uploaded.

SHA-1 has practical collisions. Use SHA-256 for anything new.

Text (hashed as UTF-8)

Show all algorithms

SHA-1

Compare with a checksum

What it does

SHA-1 produces a 160-bit digest (40 hex characters). Git used it for object IDs and many older checksums use it.

SHA-1 is broken for collision resistance: researchers produced two different PDFs with the same SHA-1 in 2017. Use SHA-256 for anything new.

How to use it

Type text or choose a file.
Choose hex or Base64.
Compare with a known checksum if you have one.

Example

Input

abc

Output

a9993e364706816aba3e25717850c26c9cd0d89d

Things to watch for

SHA-1 is unsuitable for signatures and certificates. Browsers rejected SHA-1 certificates in 2017.
HMAC-SHA1 is still considered safe, because HMAC does not rely on collision resistance. Use the HMAC tool for that.

Questions

How do I check a file’s SHA-1 checksum?: Choose the file, paste the published checksum into Compare, and the tool says whether they match. On the command line: sha1sum file.
Is the file uploaded?: No. It is read and hashed in your browser. Files up to 512 MB are supported.
Why is my hash different from another tool’s?: Usually a trailing new line (echo adds one; use printf %s), a different character encoding, or Windows line endings. This tool hashes the exact UTF-8 bytes of the text.
Can a hash be reversed?: No. But short or common inputs can be found by guessing, which is why plain hashes are not suitable for passwords.