Nonce of Ethereum Account

A unique transaction counter associated with an Ethereum account to ensure each transaction is processed only once, preventing replay attacks.

What is Nonce of Ethereum Account?

In Ethereum, the account nonce is a numerical value associated with each account that tracks the number of transactions sent from that account, used to prevent replay attacks and ensure proper transaction ordering. Each time an account (externally owned account or contract) initiates a transaction, the nonce is incremented by one, and this value is included in the transaction data. Nodes verify that the transaction’s nonce matches the account’s current nonce to validate it, ensuring that transactions are processed sequentially and cannot be reused maliciously.

The nonce starts at 0 for a new Ethereum account and increases with every transaction, including transfers of ETH, token transactions, or smart contract interactions. For example, if an account has a nonce of 5, the next transaction must include a nonce of 6 to be valid; a transaction with a nonce of 4 or 7 would be rejected or queued until prior nonces are processed. This mechanism prevents attackers from resubmitting a previously valid transaction (a replay attack) across Ethereum’s mainnet or compatible networks, as seen in a 2016 incident where poor nonce management in a wallet led to transaction failures.

Nonce management is critical for Ethereum users, especially in high-throughput scenarios like DeFi trading, where incorrect nonces can cause transaction delays or rejections. Wallets like MetaMask automatically handle nonce assignment, but manual nonce adjustments are sometimes needed for replacing or canceling pending transactions by submitting a new transaction with a higher gas price and the same nonce. As of 2025, Ethereum’s account nonce remains a core security feature for transaction integrity.