Bitcoin at the cashier
Bitcoin is the slowest and most expensive of the crypto rails a cashier normally lists, and it is still the one most people already own. Both facts matter here. The general logic of blockchain payments is set out on the crypto page; this one deals with what is specific to Bitcoin.
Average block
~10 min
Confirmations
2–3
Minimum
~20 € equiv.
Fee paid to
The network
Why the wait varies so much
A block is found roughly every ten minutes, but a transaction only enters a block if the fee attached to it competes with everything else waiting. When the queue of unconfirmed transactions is short, a deposit clears in twenty minutes. When it is long, an underpriced transfer can sit for hours without anything being wrong with it. This is the single largest difference between Bitcoin and the faster chains: the delay is auction-driven, not fixed.
The fee decides the minimum
Because the sender pays for priority, the sensible minimum deposit rises and falls with network conditions. Sending twenty euros when the fee is a few cents is perfectly reasonable; sending the same twenty when the network is busy can mean losing a visible slice of it before it arrives. A wallet that lets the fee be chosen manually is useful for exactly this reason — and lowering it below the suggested rate buys nothing except a longer wait.
The euro figure moves in transit
The playing balance is in euros, so the coin is converted on arrival at whatever the rate is at the moment of crediting. Between pressing send and reaching confirmation, that rate has had thirty minutes to move. Over a single deposit the effect is small; over the round trip from deposit to eventual payout it is the main reason the number that comes back does not match the number that went in. A dollar-pegged stablecoin removes this entirely, at the cost of introducing a second chain to choose from.
Payouts
A Bitcoin withdrawal waits in the operator's approval queue like any other request; the chain contributes only the final thirty to sixty minutes. The advantage appears at the weekend, when a bank rail is standing still and the network is not. The first request is slower regardless, because that is when identity is verified and the wallet address is bound to the account — a step performed once and never repeated.
When a transaction seems stuck
An unconfirmed transaction is not a lost one. It is visible on any public explorer using its hash, and it will confirm when fee conditions allow. Keeping that hash until the balance changes is the whole of the required diligence: it is the only thing that proves a transfer exists, and it is the first thing support will ask for. Address accuracy deserves the same care, since a Bitcoin payment sent to the wrong destination has no recall mechanism of any kind.