I heard about many use: Bitcents, Bitmills (or Bitmilles)

1.02 - One bitcoin and two bitcents
0.001 - One millibitcoin (nickname "one Millie")
0.000001 - One microbitcoin (nickname "one Mike")
0.00000001 - The bitcoin base unit (nickname "one Satoshi")

millicoins, microcoins, and nanocoins

Which are the official naming conventions and should Bitcoin be capitalized when you are referring to the unit?


2 Answers 2


Prevalent units of bitcoin

To my knowledge, only bitcoin and satoshi are subunits universally used for Bitcoin.
As of 2014/2015, one also often sees bit as a moniker for one microbitcoin, i.e. 100 satoshis.

BTC has been used as the abbreviation for bitcoin for a long time, yet, in September bitcoin was added to ISO 4217, as XBT, where X means not associated with a country, just as in XAG (Silver) and XAU (Gold), and opposed to national currencies, e.g. USD (US Dollar). However, it seems to me that XBT has not been adopted by the community, BTC remains prevalent.

Origin of millibitcoin and microbitcoin

Millibitcoin and microbitcoin follow the conventions of the International System of Units, and thus are derived from the main unit bitcoin with a prepended "m" for millibitcoin and a prepended "μ" for microbitcoin.
Following the same conventions and starting from the common abbreviation BTC for bitcoin, one would use mBTC and μBTC.

Millibit and microbit are confusing

While usually people will understand the meaning, using the abbreviations "millibit" or "microbit" gives the impression that they are assiociated with bit as the main unit. This is especially confusing with the advent of bit as a nickname for microbitcoins.


Bit is a terrible name for two reasons: Bit, the binary digit, is the basic unit of information. It is used a lot in the context of anything related with computers and therefore shouldn't be doubled as a subunit of bitcoin. Second, due to people using "millibit" and "microbit" it is terribly confusing to anyone that is new to Bitcoin, but familiar with the International System of Units.

Millie and Mike

"Millie" and "Mike" were proposed nicknames for millibitcoin and microbitcoin, but I haven't seen them get much usage. I don't think that they will see adoption.

Units in English

In general currencies are not capitalized in English, unlike the name of the protocol. So, you would write about the Bitcoin protocol, but five bitcoins.


I would argue for the following usage of units:

Unit       Value in bitcoins  Value in satoshis   Abbreviation   Symbol
bitcoin        1.0               100,000,000             BTC        ₿
millibitcoin   0.001                 100,000            mBTC       m₿
microbitcoin   0.000001                  100            μBTC       μ₿
bit            0.000001                  100             bit        ƀ
satoshi        0.00000001                  1         satoshi        ṩ

Note that there neither bit nor satoshi have a widely used symbol, and these two are my personal preference.


So, the question is, what is mBTC?

Well, for starters, there are quite a few different mBTC tokens, and they can stand for multiple things because there are multiple tokens with mBTC. So, to begin, I have two notes with 20 mBTC on them. They are Blockchain bitcoin notes. Based on what I assume and studied, they might be 'Mirrored Bitcoin', because if it were 'millibitcoin', I would have a note that says '0.00' followed by some BTC amount in mBTC.

Therefore, the number 20, representing the coins, must be greater than 1.0 or equal to 1.0 to have 20 coins equaling 20.0 mBTC. From my study, I found that there are several mBTC variants: Mirror Bitcoin, microbitcoin, Moon Bitcoin, Bitcoin Chromatic, Meta Bitcoin, Mstable Bitcoin, and millibitcoin. All of these are mBTC denominations. So, if your coin's value starts with a number before the decimal point in the equation, you have more than one coin. It's not 1 millibitcoin, as having less than one coin would result in a millibitcoin.

  • Hi Kyle, I don’t understand how your answer relates to the question. I have never heard of “Mirror Bitcoin, Moon Bitcoin, Bitcoin Chromatic, etc.” as subunits of a bitcoin. Do you perhaps want to take another look at this?
    – Murch
    Commented Aug 28, 2023 at 14:27
  • Do you mean notes as in paper currency bank notes? Something like pseudo-accounting entries?
    – Mercedes
    Commented Aug 30, 2023 at 16:41
  • If you have a new question, please ask it by clicking the Ask Question button. Include a link to this question if it helps provide context. - From Review
    – Mercedes
    Commented Aug 30, 2023 at 16:42

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