TradePortfolio

Checksum Address Converter

Convert any Ethereum address to its EIP-55 checksummed format or verify an existing checksum.

Formula

EIP-55 Checksum

Each character in the address is uppercased if the corresponding nibble in the keccak256 hash of the lowercase address is ≥ 8.

Examples

Example 1: Lowercase to checksummed
  • Input: 0xd8da6bf26964af9d7eed9e03e53415d37aa96045
  • Hash the lowercase address (without 0x)
  • For each character: uppercase if hash nibble ≥ 8
0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045
Example 2: Already checksummed
  • Input: 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045
  • Convert to lowercase, recompute checksum
  • Compare: matches!
Valid checksum — the address has not been tampered with.
Example 3: Invalid checksum
  • Input: 0xD8DA6BF26964AF9D7EED9E03E53415D37AA96045
  • Convert to lowercase, recompute checksum
  • Compare: doesn't match the input capitalization
Invalid checksum — the mixed case doesn't match EIP-55. May be all-caps (no checksum).

Key Concepts

What is EIP-55?

EIP-55 is a checksum standard for Ethereum addresses. It encodes a checksum in the capitalization of hex characters. If someone changes a character, the capitalization pattern breaks, alerting you to the error.

How It Works

Take the keccak256 hash of the lowercase address. For each character in the address, if the corresponding hash nibble is ≥ 8, capitalize it. This produces a mixed-case address that serves as its own checksum.

Backward Compatible

All-lowercase and all-uppercase addresses are still valid — they just lack the checksum protection. Most wallets and dApps now use checksummed addresses by default.

Error Detection

EIP-55 catches single-character errors with very high probability. If you accidentally change one character in a checksummed address, the checksum will fail, preventing you from sending to the wrong address.

Cross-Chain Compatibility

EIP-55 works for all EVM chains. A checksummed Ethereum address is also a valid checksummed Polygon, Arbitrum, or BSC address.

Smart Contract Addresses

Contract addresses follow the same format as EOA (externally owned account) addresses. Both can be checksummed. There's no way to tell from the address alone if it's a contract or an EOA.

Understanding EIP-55 Checksums

Ethereum addresses are 160-bit (20-byte) values, typically displayed as 40 hexadecimal characters with a 0x prefix. Without a checksum, it's easy to accidentally send funds to a mistyped address with no way to recover them.

EIP-55 solves this by encoding a checksum directly into the capitalization of the hex characters. No extra characters are added — the address stays 42 characters long. The capitalization pattern is deterministic, computed from the keccak256 hash of the address.

This converter computes the checksum entirely in your browser. Paste any Ethereum address to get its checksummed form, or verify whether an existing address has a valid EIP-55 checksum.

Frequently Asked Questions

Is a lowercase address invalid?

No — all-lowercase addresses are valid, they just lack checksum protection. Funds sent to a lowercase address will arrive correctly. The checksum is purely an error-detection feature.

Does this work for all EVM chains?

Yes — EIP-55 checksums are chain-independent. The same checksummed address works on Ethereum, Polygon, Arbitrum, BSC, Avalanche, and all other EVM-compatible networks.

Is this computed locally?

Yes — the keccak256 hash and checksum are computed entirely in your browser. Your address is never sent to any server.