Satoshi (sat)
Also called: sat, sats, satoshis, smallest bitcoin unit, 0.00000001 BTC, sats per vbyte.
A satoshi (sat) is the smallest unit of bitcoin: one hundred-millionth of a bitcoin, or 0.00000001 BTC. 1 BTC = 100,000,000 sats.
A satoshi, or sat for short, is the smallest amount of bitcoin the protocol can record: 0.00000001 BTC. One bitcoin is 100,000,000 satoshis. The unit is named after Bitcoin's creator, Satoshi Nakamoto.
How amounts really work
Bitcoin has no decimals internally. Every output stores its value as a whole number of satoshis in an 8-byte field, and the consensus rules check those integers. "0.5 BTC" is a display convention for 50,000,000 sats. The total supply is capped at just under 21 million BTC, about 2.1 quadrillion satoshis.
| Satoshis | Bitcoin |
|---|---|
| 1 sat | 0.00000001 BTC |
| 100 sats | 0.000001 BTC (one "bit") |
| 100,000 sats | 0.001 BTC (1 mBTC) |
| 100,000,000 sats | 1 BTC |
Fees are usually quoted in satoshis per virtual byte (sat/vB), see vbyte. Convert between units with the unit converter.
Proposals about naming units
Three BIPs propose conventions for naming and displaying amounts. None of them changes the protocol:
- BIP 172, by OceanSlim, proposes formally standardizing "satoshi" (plural "satoshis") and the short forms "sat" and "sats" for 0.00000001 BTC, written in lowercase.
- BIP 176, by Jimmy Song, proposes "bits" as the name for 100 satoshis, so everyday amounts need at most two decimal places.
- BIP 177, by John Carvalho, proposes calling the base unit itself "bitcoin", so ₿1 would mean what is now one satoshi, while the currency code BTC keeps meaning 100,000,000 base units.
Each takes a different view on whether decimals or whole numbers are easier for people to read. Bitcoin URIs still express amounts in decimal BTC, and very small outputs run into the dust limit.