Bitcoin unit converter: BTC, sats, bits and msat
Type an amount in any unit and the others update: bitcoin (BTC), millibitcoin (mBTC), bits (µBTC), satoshis (sats) and millisatoshis (msat). One bitcoin is exactly 100,000,000 sats, and the maths uses whole numbers, so nothing is ever rounded.
Updated · 4 min read
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How many sats are in a bitcoin?
One bitcoin is exactly 100,000,000 satoshis (sats), so one satoshi is 0.00000001 BTC, the eighth decimal place. The sat isn't just a display unit: every transaction output stores its value as a whole number of sats, and the protocol has no smaller on-chain amount. "0.5 BTC" is a convenient way to write 50,000,000 sats.
To convert by hand:
| From | To | Do this | Example |
|---|---|---|---|
| BTC | sats | multiply by 100,000,000 | 0.0025 BTC = 250,000 sats |
| sats | BTC | divide by 100,000,000 (move the point 8 places left) | 50,000 sats = 0.0005 BTC |
| mBTC | sats | multiply by 100,000 | 2.5 mBTC = 250,000 sats |
| bits | sats | multiply by 100 | 1,500 bits = 150,000 sats |
| sats | msat | multiply by 1,000 | 21 sats = 21,000 msat |
The units at a glance
- BTC (bitcoin): the unit exchanges and most wallets show. Payment links (BIP 21 and its successor BIP 321) state amounts in decimal BTC, with a dot and no commas.
- mBTC (millibitcoin): 0.001 BTC, or 100,000 sats. Some wallets offered it as a display unit.
- bits (µBTC, microbitcoin): 0.000001 BTC, or 100 sats. BIP 176 proposes "bits" as the name.
- sats (satoshis): 0.00000001 BTC, the smallest amount a transaction output can hold. Fee rates are quoted in sats per vbyte.
- msat (millisatoshis): 0.001 sat. Used by the Lightning Network for payments and routing fees.
Why this converter doesn't round
Many calculators store numbers as binary floating point, which can't represent most decimals exactly. In JavaScript, 0.29 × 100,000,000 gives 28,999,999.999999996, not 29,000,000, and 0.1 + 0.2 gives 0.30000000000000004. Rounding usually hides the error, but with money it's better to avoid it. This tool reads what you type as text and does all its arithmetic in whole millisatoshis with arbitrary-size integers, so 1 BTC is always exactly 100,000,000,000 msat. It accepts up to 8 decimal places for BTC when you work in whole sats, and up to 11 when an amount includes millisatoshis (3 decimal places on the sats field).
You can type grouped numbers such as 100,000,000 or 100 000 000. Use a dot for decimals.
Millisatoshis and Lightning
Lightning payments can be smaller than one sat: Lightning software tracks balances and fees in millisatoshis. That precision exists only inside Lightning channels. When a channel's funds are settled on the blockchain, the outputs hold whole sats, because a transaction output can't hold a fraction of a satoshi. If you enter an amount with a fraction of a sat, the converter points this out. The Lightning Network guide explains which BIPs Lightning relies on.
How many bitcoin will ever exist?
Exactly 20,999,999.9769 BTC (2,099,999,997,690,000 sats), just under 21 million. The block subsidy started at 50 BTC and halves every 210,000 blocks. The software computes it in whole sats by shifting bits to the right, which rounds down at each halving, so the total falls slightly short of 21 million. The subsidy reaches zero after the 33rd halving.
BIP 42, by Pieter Wuille, fixed a quirk in that code: the shift was undefined after 64 halvings, and in practice the subsidy would have started over at 50 BTC. BIP 42 was written tongue in cheek on 1 April 2014, but the fix is real: the subsidy now stays at zero, so the supply is finite. The total also counts the 50 BTC in the genesis block, which BIP 42 notes can't actually be spent. Enter "Max supply" above to see the figure in every unit.
What should the units be called? BIPs 176, 172 and 177
Three informational BIPs propose names for bitcoin's units. None of them changes the protocol; they are about how wallets display amounts.
- BIP 176 (Jimmy Song, 2017) proposes "bits" for 100 sats (1 µBTC). Its argument: once a bitcoin is worth thousands of dollars, small amounts have many confusing decimal places, and bits need at most two.
- BIP 172 (OceanSlim, 2025) proposes formally standardizing "satoshi" (plural "satoshis") as the name for 0.00000001 BTC, with "sat" and "sats" as the short forms. It presents itself as the least disruptive option, formalizing what many people already say.
- BIP 177 (John Carvalho, 2025) proposes redefining "bitcoin" to mean the base unit itself, so that what is called 1 sat today would be "1 bitcoin", while the currency code BTC keeps its meaning of 100,000,000 base units. Its argument is that whole numbers match how the ledger works and avoid decimal confusion.
Supporters of each argue it is the clearest for newcomers; critics point to the confusion of having several names, or of changing what "bitcoin" means. This converter uses today's common terms. See What is a BIP? for how proposals like these are discussed.
Frequently asked questions
How many satoshis are in one bitcoin?
Exactly 100,000,000. One satoshi (sat) is 0.00000001 BTC, the eighth decimal place, and it is the smallest amount a Bitcoin transaction output can hold. So 0.001 BTC is 100,000 sats, and 1,000 sats is 0.00001 BTC.
How do I convert sats to BTC?
Divide the number of sats by 100,000,000, which is the same as moving the decimal point eight places to the left. For example, 50,000 sats = 0.0005 BTC and 2,500,000 sats = 0.025 BTC. To go the other way, multiply BTC by 100,000,000.
What is a bit in bitcoin?
A bit is 100 sats, or one millionth of a bitcoin (0.000001 BTC), the same amount as a microbitcoin (µBTC). The name was proposed in BIP 176 by Jimmy Song so that everyday amounts need at most two decimal places. 1 BTC is 1,000,000 bits.
What is a millisatoshi (msat)?
One thousandth of a satoshi, or 0.00000000001 BTC. The Lightning Network uses millisatoshis to track balances and fees precisely, so a Lightning payment can include a fraction of a sat. On the blockchain itself, amounts are always whole sats, so fractions only exist inside Lightning channels.
How many bitcoin will ever exist?
20,999,999.9769 BTC, slightly under 21 million. The block subsidy halves every 210,000 blocks and is calculated in whole sats, rounding down each time, until it reaches zero after the 33rd halving. BIP 42 made sure it stays at zero. That total is 2,099,999,997,690,000 sats.