Satoshi (unit)
TL;DR
A satoshi (sat) is the smallest divisible unit of Bitcoin: 1 BTC = 100,000,000 satoshis.
The satoshi is named after Bitcoin's anonymous inventor. With 100 million satoshis per BTC, Bitcoin is divisible to eight decimal places. For microtransactions (tipping, in-game purchases, Lightning payments) sats are the practical unit.
Example
A coffee costs €3.50 — roughly 4,200 sats at a BTC price of €83,000. On Lightning this is a sub-second transaction with 1–2 sat fees.
Frequently asked questions
Is there anything smaller than a satoshi?
On Bitcoin base layer: no. On Lightning there is 'millisatoshi' (0.001 sat) for precise routing, but on-chain the sat is minimum.
Related terms
Further reading
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