There are 100,000,000 satoshis in a bitcoin, so one satoshi is 0.00000001 BTC: one hundred-millionth of a coin, eight decimal places down. The figure is not a convention exchanges settled on. Bitcoin Core’s source code fixes it in one line of its consensus rules, and every amount that code handles is a whole number of satoshis.
How many satoshis in a bitcoin, according to the code?
This desk read Bitcoin Core’s consensus header, src/consensus/amount.h, on the project’s master branch on 17 October 2026. The type every amount uses is commented “Amount in satoshis”; the constant is COIN{100'000'000}, under the comment “The amount of satoshis in one BTC.”
So a wallet showing 0.5 BTC is holding 50,000,000 satoshis. The unit is named after Satoshi Nakamoto, Bitcoin’s pseudonymous creator.
Satoshi to bitcoin: the conversion table
Arithmetic from that constant, with no prices.
| Satoshis | Bitcoin (BTC) |
|---|---|
| 1 | 0.00000001 |
| 100 | 0.000001 |
| 1,000 | 0.00001 |
| 100,000 | 0.001 |
| 1,000,000 | 0.01 |
| 100,000,000 | 1 |
Anyone holding part of a coin, however it was paid for (including by credit card), holds satoshis.
How many satoshis are there in total?
The usual answer is 2.1 quadrillion: 21 million bitcoin times 100 million. River Financial’s explainer, which ranks for this question, says there will “only ever be 2.1 quadrillion satoshis in existence”. The arithmetic is right; the framing is firmer than the code.
The same file sets MAX_MONEY at 21,000,000 × COIN, that 2.1 quadrillion, but its comment says the constant is not the total money supply, which “currently happens to be less than 21,000,000 BTC for various reasons”. It is a sanity check: a ceiling, not a count.
New coins come from the block subsidy in validation.cpp: 50 × COIN per block, halved every 210,000 blocks (“approximately every 4 years”, per the code) and forced to zero once halvings reach 64. Each halving is a binary shift on whole satoshis, so odd amounts round down; our reading is that this is one of those reasons, though the code does not say so. We print no final supply figure.
Is spending satoshis a disposal for UK tax?
HMRC’s CRYPTO22200 says each type of token needs its own pool, naming bitcoin, and that the pool changes “with each acquisition, part disposal or disposal”. That CRYPTO22200 page does not use the word satoshi, but on its terms spending a few thousand sats can be a part disposal from your bitcoin pool for Capital Gains Tax. For what people actually declare, see HMRC’s first crypto gains numbers.
Questions readers ask
Is there really 1 bitcoin, or just 100 million satoshis?
Both. Bitcoin Core stores every amount as a whole number of satoshis, and 1 BTC is the label for 100,000,000 of them, the COIN constant in its consensus code. A whole bitcoin is not a separate object on the network, which is why a holding of 0.01 BTC is as real as a whole coin.
How do I convert bitcoin to satoshis?
Multiply by 100,000,000: 0.005 BTC is 500,000 satoshis. To go back, divide satoshis by 100,000,000, or move the decimal point eight places to the left. Because Bitcoin Core counts in whole satoshis, an amount with more than eight decimal places of BTC is not one its base-layer amounts can hold.
What is a satoshi worth?
One hundred-millionth of whatever a bitcoin is worth when you ask. Coin Brief does not quote prices, which move by the minute; a converter showing a satoshi in pounds is multiplying the current bitcoin price by 0.00000001. The unit is constant. What it buys is not.
Worth saying plainly: knowing the unit is not knowing the risk. Crypto assets are high risk, a satoshi is as volatile as the bitcoin it belongs to, and nothing here is advice. Your tax position is a question for HMRC or a qualified adviser.