A microbitcoin (μBTC) is a unit of Bitcoin (BTC) equal to one millionth of a bitcoin, or 0.000001 BTC. Because the smallest unit of bitcoin, the satoshi, is one hundred-millionth of a bitcoin, one microbitcoin equals exactly 100 satoshis. The prefix "micro" comes from the metric system, and the symbol uses the Greek letter mu (μ); where that character is not available, the unit is often typed as "uBTC".
The microbitcoin is also known as a "bit", a name formally proposed in Bitcoin Improvement Proposal 176 in 2017. It sits between the millibitcoin (mBTC, one thousandth of a bitcoin) and the satoshi. These units do not exist separately on the Bitcoin blockchain, which records every amount as a whole number of satoshis; they are display conventions used by wallets, exchanges and writers. The name should not be confused with MicroBitcoin (MBC), an unrelated coin created in 2018 by a hard fork of the Bitcoin chain.
The microbitcoin in plain terms
Think of how a dollar can be written as 100 cents. Nobody prices a coffee as "0.0450 thousand dollars"; we pick a unit that keeps the numbers readable. Bitcoin's units work the same way. When one bitcoin is worth a large sum, everyday amounts become tiny fractions with many zeros after the decimal point, which are easy to misread.
The microbitcoin moves the decimal point six places. An amount such as 0.00067 BTC becomes 670 μBTC, or 670 bits, which reads like a normal price. It is the same money; only the label changes.
Conversions and worked examples
The conversion between bitcoin and microbitcoin is:
where is the amount in whole bitcoin and is the same amount in microbitcoin. Since one bitcoin is satoshis, it follows that satoshis.
| Unit | Value in BTC | Value in satoshis |
|---|---|---|
| Bitcoin (BTC) | 1 | 100,000,000 |
| Millibitcoin (mBTC) | 0.001 | 100,000 |
| Microbitcoin (μBTC, bit) | 0.000001 | 100 |
| Satoshi (sat) | 0.00000001 | 1 |
Worked example: a payment of 0.0025 BTC is μBTC, which is satoshis. At an illustrative price of $80,000 per bitcoin, one microbitcoin would be worth US dollars, or 8 cents, so 2,500 μBTC would be $200. On the supply side, Bitcoin's cap of 21 million bitcoins equals 21 trillion microbitcoins.
BIP 176 and the name "bits"
BIP 176, "Bits Denomination", was written by Jimmy Song and created on 12 December 2017. It is an informational proposal, still marked as a draft, that defines one bit as 100 satoshis and recommends the name for user interfaces. Its argument was practical: as the price of bitcoin rose, retail amounts needed many decimal places, which makes it hard for people to compare them with prices in fiat currency and easy to make costly mistakes. In its example, at $15,000 per bitcoin, $10.05 is hard to read as 0.00067 BTC but clear as 670 bits. Like other Bitcoin Improvement Proposals (BIPs) of its type, it changes no consensus rule, and no wallet is obliged to adopt it.
Use in wallets and payments
Several wallets, including the Bitcoin Core graphical interface, let users choose between BTC, mBTC, μBTC and satoshis as the display unit, and a few wallets offered "bits" as an option. In practice the "bits" label never became the standard. Since the late 2010s, the satoshi, often shortened to "sats", has become the more common small unit, especially for microtransactions on the Lightning Network and for quoting transaction fees in satoshis per virtual byte.
The choice of unit has no effect on what is recorded on chain. A crypto wallet converts the display amount to satoshis before it builds a transaction, and every input and output in the unspent transaction output (UTXO) set is stored as an integer number of satoshis. Similarly, mining pools often show small daily earnings in sats or μBTC so that miners can track them without long strings of zeros.
Limitations and confusion
Having four units for one asset invites error. A user who confuses mBTC with μBTC is off by a factor of 1,000, and some older wallets and exchanges defaulted to mBTC, which caused mistaken payments. The word "bits" is also ambiguous, since it already means binary digits in computing, and the μ symbol is hard to type on many keyboards, which is one reason "uBTC" appears so often. The microbitcoin is also easily confused with the MicroBitcoin coin mentioned above, which has its own ticker and is not a unit of bitcoin at all. Comparable display units exist on other networks, such as gwei and wei for Ethereum (ETH), where gwei is the usual unit for gas prices.