What are block confirmations and finality?

Block confirmations track a transaction’s inclusion in a valid chain and the blocks following it. Finality describes the security conditions that would have to break for a record to be reversed.

Bitcoin gains probabilistic confidence as cumulative work grows. Ethereum finalizes checkpoints through the required stake-weighted votes. The same number of blocks on two networks does not imply the same security.

Example: counting six confirmations

Suppose a Bitcoin transaction appears at height 900,000 and the chain tip reaches 900,005. Including its own block, the count is 900,005 − 900,000 + 1 = 6. Six confirmations are not a mandatory or risk-free threshold for every payment; the recipient may apply a different acceptance policy.

Ethereum can continue producing blocks while finality stalls. The PoS FAQ explains the basis for finality. An exchange crediting a deposit is a separate service event. Finality does not grant a cancellation right for a transfer to the wrong address.

Our PoW versus PoS comparison evaluates attack limits and participation requirements on common criteria.