Satoshi (sat)
A satoshi is one hundred-millionth of a bitcoin. Bitcoin’s software counts every amount in satoshis and only converts to BTC for display.
Photo: “Pretty Penny” by JD Hancock, CC BY 2.0, via Flickr (edited: cropped and resized).
A satoshi (sat) is the smallest unit of bitcoin recorded on the blockchain: 0.00000001 BTC, so 100,000,000 satoshis make one bitcoin [1]. Bitcoin Core defines one BTC as exactly 100,000,000 satoshis in its code [2]. The unit is named after Bitcoin’s creator, Satoshi Nakamoto.
Key points
- 11 BTC = 100,000,000 satoshis; 1 satoshi = 0.00000001 BTC.
- 2Amounts on the blockchain and in Bitcoin’s code are whole numbers of satoshis.
- 3You never need to buy a whole bitcoin; prices and fees are often quoted in sats.
Where does the satoshi come from?#
Bitcoin Core’s consensus code stores every amount as a whole number of satoshis and defines the constant COIN as 100,000,000 — the number of satoshis in one BTC [2]. The Bitcoin Wiki notes that all amounts on the blockchain are denominated in satoshis before being converted for display, and that the 100-million division was decided by Satoshi Nakamoto no later than November 2008 [1]. The name came later from forum users and caught on as a tribute to Bitcoin’s pseudonymous creator [1].
| Step | Value |
|---|---|
| 0.0025 BTC × 100,000,000 | 250,000 sats |
| 0.5 BTC × 100,000,000 | 50,000,000 sats |
| Value of 1 sat if 1 BTC = $80,000 | $0.0008 |
| $10 at that price = 10 ÷ 0.0008 | 12,500 sats |
Try your own numbers with the satoshi converter.
| Unit | In BTC | Where you see it |
|---|---|---|
| Bitcoin (BTC) | 1 | Prices and balances |
| Bit (proposed in BIP-176) | 0.000001 (100 sats) | Proposed as a friendlier unit |
| Satoshi (sat) | 0.00000001 | Fees, small payments, code |
| Millisatoshi (msat) | 0.00000000001 | Lightning payment channels |
The bit and millisatoshi are described in the Bitcoin Wiki [1]. A millisatoshi cannot be recorded on the blockchain itself.
Why does the satoshi matter to beginners?#
It removes the idea that you need a whole bitcoin. Buying 0.0025 BTC is buying 250,000 sats, and many apps let you see your balance that way. Transaction fees are also quoted per unit of transaction size in sats — see transaction fees explained. And because the satoshi is the smallest recordable unit, Bitcoin’s supply schedule rounds away fractions of a satoshi, which is why total issuance ends just under 21 million BTC (Bitcoin halving explained).
Which words are related?#
- Halving — the scheduled cut in new bitcoin per block, counted in satoshis by the code.
- UTXO — each unspent output holds a whole number of satoshis.
- Mempool — where transactions wait, ranked largely by their fee rate in sats.
Frequently asked questions#
How many satoshis are in one bitcoin?
Exactly 100,000,000. Bitcoin Core’s code defines one BTC as 100,000,000 satoshis [2].
Is the plural “satoshi” or “satoshis”?
Both are used. The Bitcoin Wiki says the traditional plural is simply satoshi, but satoshis is also popular and equally correct [1]. Many people just say sats.
Can the satoshi be divided further on-chain?
No. The satoshi is the finest amount the blockchain can record; smaller units such as the millisatoshi exist only inside payment channels [1].
Sources#
Grade A = primary source (regulator, protocol specification, client code, original author). Grade B = expert secondary source used for explanation only.
- BBitcoin Wiki. Satoshi (unit), 2026.
- ABitcoin Core (GitHub). src/consensus/amount.h (COIN, MAX_MONEY), 2026.