Keccak-256 Hash CalculatorNew
Calculate a Keccak-256 hash from text using this free online calculator. The 256-bit digest updates as you type and is displayed as 64 hexadecimal characters. Hashing runs locally in your browser.
What is Keccak-256?
Keccak-256 is a cryptographic hash function based on the Keccak sponge construction. It produces a fixed 256-bit (32-byte) digest for any input length. Keccak was selected as the basis for the SHA-3 standard, but the original Keccak-256 and standardized SHA3-256 use different domain-separation padding and produce different results.
Keccak-256 is used in Ethereum for transaction and data hashing, address derivation, and function selectors. It is a one-way function: a digest cannot feasibly be reversed to recover an arbitrary original input.
Keccak-256 vs. SHA3-256
| Feature | Keccak-256 | SHA3-256 |
|---|---|---|
| Output | 256 bits (64 hex characters) | 256 bits (64 hex characters) |
| Construction | Keccak-f[1600] sponge | Keccak-f[1600] sponge |
| Domain-separation suffix | 0x01 | 0x06 |
| Same hash for identical input? | No | No |
| Typical usage | Ethereum ecosystem | Standardized SHA-3 applications |
Do not substitute SHA3-256 for Keccak-256 when implementing Ethereum-compatible hashing. Although both output 256 bits, their digests differ.
Example Keccak-256 hashes
| Input text | Keccak-256 digest |
|---|---|
| Empty string | c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 |
abc | 4e03657aea45a94fc7d47ba826c8d667c0d1e6e33a64a036ec44f58fa12d6c45 |
The calculator converts input text to UTF-8 bytes before hashing. Even a change in whitespace or capitalization changes the digest.
How to use this calculator
- Enter or paste the text to hash. The Keccak-256 digest updates automatically as you type.
- Select Copy Keccak-256 hash to copy the 64-character hexadecimal result to your clipboard.
- Enable Uppercase output if you prefer uppercase hexadecimal characters.
- Select the clear button or press ESC to clear the input.
Security considerations
Keccak-256 is suitable for cryptographic hashing when the protocol explicitly requires it. It is not encryption and cannot be decrypted. It is also not suitable by itself for password storage: use a password-hashing function such as Argon2id, bcrypt, or scrypt instead.
This tool hashes text, not raw files or hexadecimal byte sequences. For example, typing 0x1234 hashes those six text characters, not the two bytes 12 34.
Frequently asked questions
Is Keccak-256 the same as SHA3-256?
No. Both use the Keccak sponge construction, but their domain-separation padding differs, so the resulting digests are different.
Is Keccak-256 used by Ethereum?
Yes. Ethereum uses legacy Keccak-256 rather than standardized SHA3-256 in several core operations, including hashing used in addresses and function selectors.
Can a Keccak-256 hash be reversed?
No practical method can recover an arbitrary original input from its hash. Short or predictable inputs can still be guessed and checked.
How long is a Keccak-256 hash?
It is always 256 bits, or 32 bytes, typically shown as 64 hexadecimal characters.
Related tools
- SHA-256 hash calculator — Calculate SHA-2 hashes for general-purpose integrity checks.
- SHA-2 hash calculator — Compare SHA-2 digest variants.
- SHA-512 hash calculator — Generate 512-bit SHA-2 digests.
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