SHA-256 Hash Calculator
SHA-256 digest for any text up to 500 characters.
What it does
SHA-256 compresses any text into a fixed 256 bit fingerprint rendered as 64 hex characters. Verification compares digests instead of files: matching hashes mean matching content with overwhelming odds.
The tool above hashes up to 500 characters in your browser. It returns the digest with bit size and input length beside it.
The default abc digests to ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad, the most quoted test vector in cryptography. Empty input gives e3b0c442...b855 instead.
The algorithm follows NIST FIPS 180-4 with MDN Web Crypto references matching browser behavior. Both treat SHA-256 as one way: verification only runs forward.
How to use
- Type the text up to 500 characters.
- Read the 64 char digest first.
- Compare digests to verify downloads.
- Change one letter to watch avalanching.
- Never hash passwords alone; use argon2 or bcrypt.
Formula
- 256
- Digest bits: 64 hex chars.
- 64 rounds
- Mixing passes per block.
- UTF-8
- Byte encoding before hashing.
Unicode encodes as UTF-8 first, so emoji cost four bytes each. File hashing needs upload tools; this page hashes typed text.
Worked example
Example: hash abc
Default text abc.
- Bytes: 97, 98, 99 with padding to one block.
- 64 rounds mix the eight starting words.
- Digest: ba7816bf...f20015ad (64 chars).
- Size: 256 bits from 3 chars in.
- Tool shows the full digest with sizes.
Reference table
| Input | SHA-256 starts | Length |
|---|---|---|
| (empty) | e3b0c442... | 64 chars |
| abc | ba7816bf... | 64 chars |
| Hello | 185f8db3... | 64 chars |
Limits
- Text only to 500 chars; files need other tools.
- One way: verification only, no decryption.
- Unsalted fast hashes suit files, not passwords.
- Display truncations shown with ellipsis here.
Common mistakes
- Hashing passwords without salt and work factors.
- Comparing truncated digests as proof.
- Mixing UTF-8 with other encodings.
- Reading hash as encryption.
- Trailing spaces changing digests silently.
Try it yourself
Quick checks. Answers sit tucked under each question.
Digest of empty?
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855.
Digest of Hello?
185f8db32271fe25f561a6fc938b2e264306ec304eda518007d1764826381969.
Change abc to abd?
Totally different digest: avalanching.
Questions
What is SHA-256?
A 256 bit one way fingerprint: abc always gives ba7816bf...f20015ad.
Can hashes decrypt?
No. Verification rehashes and compares instead.
Why 64 chars?
256 bits render as 64 hex digits.
Passwords with SHA-256?
Never alone. Use salted slow hashes like argon2 or bcrypt.
What changes digests?
Any single bit: avalanching rewrites about half the chars.
Local or uploaded?
Local. This page computes in your browser only.