Millibitcoin (mBTC)

A millibitcoin, abbreviated mBTC, is a fractional unit of bitcoin equal to one-thousandth of a whole coin. Because 1 BTC splits into 100,000,000 satoshis, a single mBTC works out to exactly 100,000 sats, and 1,000 mBTC make up 1 BTC.

The unit follows the same metric-style prefix system used for other bitcoin denominations, sitting between the whole coin and smaller fractions such as the microbitcoin (μBTC, also called a "bit"), which equals just 100 satoshis. This layered structure emerged organically as bitcoin's price climbed and pricing everything in whole coins, with their eight decimal places, became impractical for everyday amounts.

• Trading platforms and some exchanges use mBTC to quote order sizes and balances in more readable figures than long strings of decimals.
• Micropayment and gaming platforms have historically used mBTC as a display unit for smaller transactions.
• Some wallet software lets users toggle between BTC, mBTC, and satoshis depending on the size of the amount being handled.

In practice, the satoshi, and its shorthand "sat", has become the dominant small-unit convention across wallets and the Lightning Network, largely displacing mBTC and the bit for everyday use. Even so, mBTC remains a recognized denomination that traders and older interfaces still reference, and understanding it helps when converting between different displayed formats of bitcoin balances.