Keccak-256 at a glance
| Output | 256 bits |
|---|---|
| Padding byte | 0x01 (SHA3-256 uses 0x06) |
| Used by | Ethereum, Solidity keccak256(), EVM chains |
| Function selector of transfer(address,uint256) | 0xa9059cbb (first 4 bytes of the hash) |
Where it is used
Ethereum uses Keccak-256 for addresses (the last 20 bytes of the hash of the public key), transaction hashes, storage slots and the 4-byte function selectors that every contract call starts with. Type transfer(address,uint256) above and the first 8 hex characters are the selector.
Known answers
Keccak-256:
| Input | Digest (hex) |
|---|---|
| "" (empty) | c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 |
| "abc" | 4e03657aea45a94fc7d47ba826c8d667c0d1e6e33a64a036ec44f58fa12d6c45 |
| "hello world" | 47173285a8d7341e5e972fc677286384f802f8ef42a5ec5f03bbfa254cb01fad |
In code
// ethers v6
import { keccak256, toUtf8Bytes } from "ethers";
keccak256(toUtf8Bytes("hello world"));More languages: SHA-3 code examples. Other calculators: SHA3-256 · SHA3-512 · SHAKE256.
Frequently asked
Is the Keccak-256 calculator private?
Yes. The hash is computed in your browser; nothing you type or drop is uploaded.
What is the Keccak-256 of an empty string?
Keccak-256 of "" = c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470
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