Confirmations and Finality

Pending vs. confirmed

When someone sends you crypto, the transaction first waits in the mempool (a queue of unconfirmed transactions). Once it's included in a block, it has 1 confirmation. Each new block on top adds another.

Until a transaction is confirmed it can still be dropped or replaced, for example if the fee was too low. Once a chain reaches finality, the payment is effectively permanent.

Rough timing by chain

• Bitcoin / Bitcoin Cash: ~10 minutes per block; many sellers wait for 1-3 confirmations.
• Litecoin: ~2.5 minutes per block. Dogecoin: ~1 minute per block.
• Cardano: ~20 seconds per block; many exchanges wait about 15 confirmations (around 5 minutes) for full confidence.
• Ethereum: ~12 seconds per block; finalized in roughly 13-15 minutes.
• Polkadot: ~6 seconds per block; usually finalized within a minute.
• Avalanche: final in about 1-2 seconds.
• Solana, XRP, Stellar, TRON: typically seconds.

At a meetup, Garage Sale, or Small Business

Crypto Barter watches the chain and shows the payment status for you. For small items, waiting for the first confirmation is common. For bigger trades, wait for the number of confirmations the app recommends before handing the item over.

At a Small Business, checkout locks the price for the shop's payment window, so send within that time. Carryout orders show as paid, and digital downloads unlock, once the payment has the confirmations that coin needs.