SHA3-256
Compute the SHA3-256 (256-bit) cryptographic hash of any input.
Calculate SHA3-256 (SHA-3 with a 256-bit digest) of any input. Free, offline, runs entirely client-side. Read more Show less
What is SHA3-256?
SHA3-256 is one of four fixed-output variants of the SHA-3 cryptographic hash family, standardized by NIST in FIPS 202. It produces a 256-bit (32-byte) digest, shown as 64 hexadecimal characters.
SHA-3 is based on the Keccak sponge construction, which processes data differently from the Merkle-Damgard design used by SHA-1 and SHA-2. It was chosen in 2012 after an open competition and is now a mandatory companion to SHA-2 in every modern cryptographic standard, including TLS 1.3, SSH, and post-quantum signature schemes.
How to compute SHA3-256
Type or paste your input. Choose the input encoding (UTF-8, hex, or Base64). For example, the UTF-8 string abc produces:
3a985da74fe225b2045c172d6bd390bd855f086e3e9d525b46bfe24511431532
The SHA-3 family
SHA-3 comes in four fixed-output variants and two extendable-output variants (SHAKE128, SHAKE256). This tool implements SHA3-256, which produces a 256-bit digest.
For a comprehensive tool that computes every SHA-3 variant, see the SHA-3 calculator.
SHA-3 vs Keccak
SHA-3 is essentially Keccak with a specific padding rule (0x06 instead of 0x01). The original Keccak submission produced different output for the same input. Ethereum uses the original Keccak-256, not SHA3-256. See Keccak-256 if that is what you need.
FAQ
Is SHA-3 secure?
Yes. No practical attack exists against SHA-3 at any standard output size. It is approved by NIST for all unclassified applications.
SHA3-256 vs SHA-256
Both are secure. SHA3-256 has a 256-bit output and uses a different construction. SHA-2 is more widely deployed and better supported by hardware acceleration. SHA-3 is recommended as defense in depth.
When should I use SHA3-256 instead of SHA3-256?
Only when a protocol or format you are implementing specifies SHA3-256. For new systems, SHA3-256 is the standard default.
Does SHA3-256 support HMAC?
Yes. HMAC-SHA3-256 is defined in NIST SP 800-224 and is as strong as the underlying hash. For authentication without a shared secret, use the Ed25519 signature scheme instead.
Why is my hash different from another tool?
Check input encoding, trailing whitespace, and whether the other tool is using Keccak (the pre-standard version) instead of SHA-3. They are different algorithms even though they look similar.
Command line equivalent
# OpenSSL 3.x
echo -n "abc" | openssl dgst -sha3-256
# Python
python3 -c 'import hashlib; print(hashlib.sha3_256(b"abc").hexdigest())'
# Node
node -e 'const c = require("crypto"); console.log(c.createHash("sha3-256").update("abc").digest("hex"))'