Zero-confirmation transaction

A zero-confirmation transaction is a crypto payment with zero confirmations. The payment has been sent, but it hasn’t been included in a block on the blockchain yet.

What is a zero-confirmation transaction?

A blockchain is a shared digital record of transactions. Transactions are grouped into blocks. A transaction gets its first confirmation only when it’s included in a block.

After a transaction is sent, it may already be visible to the network. Nodes, or computers that check the network’s rules, can store it in their mempool. This is a waiting area for unconfirmed transactions. Not every node sees or stores exactly the same transactions.

Until the transaction is confirmed, there’s no guarantee it will eventually be included in a block. It may remain pending, disappear from mempools, or be replaced by a conflicting payment.

An example of a zero-confirmation transaction

Someone pays for a coffee with bitcoin. The store’s payment software sees the transaction right away, but it hasn’t been included in a block yet.

If the store hands over the coffee right away, it accepts a payment with zero confirmations. The store is choosing speed, but it doesn’t yet know for sure that the payment will be confirmed.

Why is a zero-confirmation transaction important in crypto?

This term comes up with crypto payments and payment processors. It refers to the choice between accepting a payment quickly or waiting for more certainty.

An unconfirmed payment may carry a risk of double spending. This means the same coins may also be spent in another, conflicting transaction. So, seeing a payment in a crypto wallet doesn’t prove that it’s final.

Even one confirmation doesn’t make a payment absolutely irreversible. More confirmations generally reduce the risk. Other networks may have different rules and guarantees for confirmations.