Satoshi

A satoshi is the smallest unit of bitcoin, equal to one hundred-millionth of one BTC (0.00000001 BTC). The unit is named after Satoshi Nakamoto, the pseudonymous creator of Bitcoin, and is often shortened to "sat" or "sats." Because the Bitcoin protocol tracks amounts in satoshis internally, every bitcoin balance is really a count of sats: one full bitcoin is 100,000,000 satoshis.

The subdivision exists so bitcoin remains usable at any price. If one BTC costs tens of thousands of dollars, buying a coffee with it means transferring a tiny fraction — and sats give that fraction a clean name. For example, instead of saying you paid 0.00025 BTC, you can say you paid 25,000 sats. Transaction fees are also commonly quoted in satoshis per virtual byte (sat/vB), a measure of how much you pay per unit of transaction size.

A common misconception is that Bitcoin is too expensive for ordinary people to buy; because BTC is divisible into 100 million sats, you can buy a few dollars' worth just as easily as a whole coin. The phrase "stacking sats" describes gradually accumulating small amounts of bitcoin over time. The word also appears capitalized as Satoshi when referring to Nakamoto the person, so context tells you whether someone means the creator or the unit.