How does Ethereum prevent double spending?

What is double spending?

Double-spending is when a user can reacquire the EtherNative cryptocurrency of the Ethereum network they spent in one transaction and spend it again in another.

How does Ethereum prevent double spending?

Ethereum blockchain prevents double spending with its following two properties:

Account balance

Ethereum follows an account-based model, and it stores the state of every account in its world state. The world state keeps the balance of every account on the Ethereum blockchain. Once a user has spent their Ether, their balance will be decremented accordingly, and once the balance hits zero, the user cannot withdraw any more Ether. Moreover, if the withdrawal amount exceeds the balance, the user cannot proceed with that transaction (as shown in the slides below).

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Distributed ledger/ distributed consensus algorithm

Ethereum blockchain does not have a permission public distributed ledger, which is visible to every node on the network. Every node verifies all the transactions in a candidate blockBlock that is proposed by miners to all other nodes to add it to their journal (local view of the blockchain)., and if a malicious/double-spending transaction is found, that block is rejected. Therefore it prevents double-spending, as shown below.

Note: In Ethereum, if the withdraw amount exceeds the account balance, it is considered as double spending. Thus, any candidate block containing such transaction is considered malicious and rejected by the nodes.

Initial state of the Ethereum blockchain
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