A millibitcoin (millibitcoin, denoted mBTC) is a fractional unit of bitcoin equal to one thousandth of a whole coin, that is, 0.001 BTC. Since bitcoin is divided into very small fractions, derivative units of measurement have been introduced for ease of perception, and the millibitcoin is one of them.

Using mBTC helps to work clearly with small amounts without operating with many zeros after the decimal point. This simplifies the display of prices, tips, micropayments and small transfers. Alongside the millibitcoin, other fractions are also used:

• 1 BTC — one whole bitcoin;
• 1 mBTC — one thousandth of a bitcoin (0.001 BTC);
• 1 satoshi — the smallest unit, one hundred-millionth of a bitcoin (0.00000001 BTC).

All these notations refer to one and the same currency and differ only in scale. The choice of unit depends on the size of the amount and the context: for large operations BTC is more convenient, for very small ones satoshi, while the millibitcoin occupies an intermediate position.