What is settlement?

The point at which a trade or transfer is final and the asset has actually changed hands.

On a blockchain, settlement is probabilistic and strengthens with each confirmation, while card and bank rails can be reversed for days. That gap is why exchanges hold crypto bought with reversible payment methods; see finality.

The word does a lot of quiet work on exchange help pages. A trade that "executes" instantly may not have settled, and an account balance that shows a number is not the same as an asset you can withdraw. Most new-buyer complaints about frozen funds are really complaints about settlement timing.

How it works

There are three separate clocks in an ordinary purchase, and they run at different speeds.

The fiat clock is the slowest and the only reversible one. A card payment can be charged back long after the purchase under the card scheme rules, and a direct debit can be recalled by the payer within the scheme's refund window. See chargeback.

The exchange clock is internal. A match on the order book moves balances in the venue's own database immediately. Nothing has touched a blockchain, and the asset exists as a claim on the exchange until you withdraw it.

The chain clock is the one people mean by settlement. On a proof-of-work chain like Bitcoin, finality is probabilistic and the chance of a reorganization falls with each block built on top. On Ethereum, the consensus specifications define an explicit finalization step: a checkpoint is justified and then finalized across epochs, which under normal conditions takes two epochs, or roughly thirteen minutes at twelve seconds per slot and thirty-two slots per epoch (source: the Ethereum consensus specifications).

Example

Illustrative timings of the kind exchanges publish. You buy $500 of Bitcoin with a debit card. The trade appears in your account at once. The exchange applies a hold on withdrawing that specific balance for several days because the card payment is reversible. A bank transfer for the same purchase might carry no hold at all once the money has arrived. Same asset, same price, different time to actually control it. The venue's own funding page is where that hold length is stated.

Why it matters when you buy

If you intend to move coins to your own wallet, the payment method decides when you can. Bank rails usually settle without a withdrawal hold; card rails usually do not. The fee comparison shows what each rail costs, and the exchange pages list which rails a venue supports in your jurisdiction.

Related terms

• finality — the chain-side version of settlement
• confirmation — the unit finality is counted in
• chargeback — why fiat legs stay reversible
• on chain off chain — where a balance actually lives
• withdrawal limit — the other reason a transfer waits

Questions

How many confirmations are enough?

It depends on the chain and on the receiving party. Exchanges publish their own required confirmation counts per asset on their deposit pages, and those numbers are the practical answer for a deposit.

Why can I trade but not withdraw?

Trading moves an internal balance. Withdrawing moves a real asset and exposes the exchange to a reversal on the fiat leg, so venues apply holds tied to the funding method.

Does an instant bank transfer settle instantly?

The payment does. Whether the exchange releases the withdrawal hold at the same moment is a policy decision published on its funding page, and some venues hold regardless of rail.