Bitcoin Units

Where you're going: Bitcoin is divisible to eight decimal places. That gives you nine possible units between "one BTC" and "one satoshi," and people have named most of them. By the end of this rabbit hole you'll know which units matter in practice, which exist for historical reasons, and how to think in any of them without doing decimal math in your head.

1. Why There Are So Many Units

Bitcoin's protocol tracks balances in satoshis. One satoshi is the smallest possible amount; one bitcoin equals 100,000,000 satoshis. Everything between those two scales is a label humans invented because the numbers got awkward.

When 1 BTC was worth $0.10 (in 2010), nobody needed smaller units. As the price climbed, "0.0001 BTC for a cup of coffee" became a typical amount, and the trailing zeros got annoying. Communities started using mBTC, then µBTC, then sats. Lightning Network operators needed even finer precision and added millisats (1/1000 of a satoshi).

The result: a forest of unit names, most of which you'll never use, and a few you'll use constantly. This rabbit hole sorts the useful from the historical.

2. The Three That Matter

If you ignore everything else, you can get through 95% of Bitcoin life with three units:

• BTC - the whole unit. Used for large amounts, quoting market prices, savings discussions.
• sat (satoshi) - the smallest unit. Used for fees, tips, microtransactions, fee rates (sat/vByte).
• msat (millisat) - one thousandth of a sat. Used inside the Lightning Network for fine routing fee precision. You'll rarely see msat directly in a wallet UI.

The other units (mBTC, µBTC, Finney) are mostly historical or community-specific. If you're learning Bitcoin in 2026, learning BTC and sats is sufficient.

3. The Full Scale

Bitcoin has eight decimal places. That means there are nine "positions" from BTC down to sat. The visualization below shows what each position represents - orange circles are the unit at that decimal place and everything finer; outlined circles are the higher-magnitude positions above it.

₿

·

The "Finney" example shows position 4 (0.0001 BTC = 10,000 sats). The four outlined circles to the left represent BTC, dBTC, cBTC, mBTC - all coarser denominations not part of this unit. The five filled circles starting at the Finney position represent the unit and everything below it down to the satoshi.

4. Every Unit, With Its Reason for Existing

Working from biggest to smallest:

BTC (Bitcoin) - the whole coin

₿

·

The base unit. Equals 100,000,000 satoshis. Used for market prices ("BTC is at $87,000"), large transfers ("I bought 0.5 BTC"), and any discussion where the amount is bigger than a few hundred dollars. There will never be more than 21 million of these in existence (see the Supply Schedule rabbit hole).

dBTC (deci-Bitcoin) - mostly unused

₿

·

One-tenth of a BTC. Has a name in theory; nobody uses it in practice. If you see it, it's usually in academic contexts or completeness-driven documentation.

cBTC (centi-Bitcoin) - also mostly unused

₿

·

One-hundredth of a BTC, or 1,000,000 sats. Theoretically the "cent" of Bitcoin. In practice, also unused. People who want this magnitude tend to just write 0.01 BTC.

mBTC (Millibitcoin)

₿

·

One-thousandth of a BTC, or 100,000 sats. Has some adoption: at typical Bitcoin prices, 1 mBTC is in the range of a meal or a small purchase, which makes it a reasonable display unit. Some wallets and merchants prefer mBTC over BTC to avoid showing leading zeros.

Finney

₿

·

One ten-thousandth of a BTC, or 10,000 sats. Named after Hal Finney, the cryptographer who received the first Bitcoin transaction from Satoshi in January 2009 and was probably the second person to ever run Bitcoin software. The name is community-honorary; you won't see it in many wallets. Worth knowing about because of who Hal was.

Unnamed (10^-5 BTC)

₿

·

One hundred-thousandth of a BTC, or 1,000 sats. Has no widely-used name. The decimal slot exists; the social convention doesn't.

µBTC (Microbitcoin) - aka "bits"

₿

·

One-millionth of a BTC, or 100 sats. BIP 176 proposed calling these "bits" - a shorter, more memorable name. The proposal had genuine adoption in some wallets (and on Coinbase for a while) but largely lost out to "sats" as the preferred small-amount unit.

Unnamed (10^-7 BTC)

₿

·

One ten-millionth of a BTC, or 10 sats. Like the 10^-5 slot, this one exists but has no name. Most wallets won't even let you specify amounts at this resolution without rounding.

Satoshis (sats) - the smallest unit

₿

·

One hundred-millionth of a BTC. The atomic unit; you cannot transact in less on the main chain. Named after Satoshi Nakamoto.

Sats have become the de-facto standard small unit in 2020s Bitcoin culture. "Stacking sats" is the common phrase for accumulating Bitcoin. Fees are typically quoted in sat/vByte. Lightning balances are often shown in sats. If BTC keeps appreciating, eventually most user-facing displays will probably default to sats.

5. The Units Table

When 1 BTC equals $1,000,000 (a milestone many expect within the next decade or two), the smaller units start to be more like familiar everyday amounts. Here's the alignment:

Name	Symbol	Fraction of BTC	Value at $1M/BTC
Bitcoin	BTC	1	$1,000,000.00
(unnamed)	-	0.1	$100,000.00
Centi-Bitcoin	cBTC	0.01	$10,000.00
Milli-Bitcoin	mBTC	0.001	$1,000.00
Finney	-	0.0001	$100.00
(unnamed)	-	0.00001	$10.00
Micro-Bitcoin	µBTC (bit)	0.000001	$1.00
(unnamed)	-	0.0000001	$0.10
Satoshi	sat	0.00000001	$0.01

At that price point: 1 sat = 1 cent, 1 bit = 1 dollar, 1 mBTC = 1,000 dollars. The naming starts to feel intuitive in a way it doesn't today. Some people argue this is when "the world will start pricing in sats" - which is plausible but not predictable.

6. Why 8 Decimals?

Satoshi Nakamoto picked eight decimal places when designing Bitcoin. There's no public record of why exactly eight. The conventional wisdom, repeated in many places, is that it was a guess: precise enough for microtransactions, broad enough to handle a long volatility curve.

At 8 decimals, Bitcoin can represent values from $1M+ (1 BTC) down to $0.01 (1 sat) - even if the dollar-per-BTC price reaches a million. That's the rough envelope the choice covers.

In some modern uses, 8 decimals is brushing up against the limit. The Lightning Network needs finer precision for routing fees, which is why it operates internally in millisatoshis (1/1000 of a sat, 11 decimals total). On-chain Bitcoin is still 8 decimals, but second-layer protocols have extended the resolution off-chain.

Could the protocol go to 10 or 12 decimals? Technically yes, but it would require a network-wide soft fork to redefine the smallest unit. No serious proposal has been made. The current scope works for the foreseeable future.

7. The Converter

Try it. Type any amount in any unit and watch the others update:

Units Converter

Fetching price…

Amount Unit BTCmBTCFinneyμBTC (bit)sat

BTC

1

mBTC

1,000

Finney

10,000

μBTC (bit)

1,000,000

sat

100,000,000

Double-check decimals. The math is local; nothing leaves your browser.

Pro tip: Double-check decimals before sending. The difference between 10,000 sats and 100,000 sats might look like a typo, but it's a 10x difference in actual value. Reputable wallets show fee rates and amounts in monospace fonts specifically to keep the decimals aligned. Use that affordance.

8. What People Actually Use

In practice, here's the breakdown of which units you'll encounter most:

You'll see BTC in:

• Market prices and exchange interfaces
• Large transfers and savings discussions
• Whitepapers and academic writing

You'll see sats in:

• Wallet balances (especially Lightning wallets)
• Tipping and microtransactions
• Fee rates (always expressed as sat/vByte)
• Stacker culture ("stacking sats")
• Nostr zaps and similar

You'll see mBTC in:

• A minority of merchant interfaces, especially European ones
• Some hardware wallet displays

You'll see µBTC ("bits") in:

• A few wallets that adopted BIP 176
• Older Coinbase interfaces (mostly retired now)

You'll basically never see:

• dBTC, cBTC, Finney, or the unnamed positions, except in this kind of comprehensive list

The natural reading-and-writing convention now is:

• Amounts under 0.01 BTC: use sats
• Amounts from 0.01 to 0.5 BTC: either, your call
• Amounts over 0.5 BTC: use BTC

That's it. Two units handle everything. The rest of this rabbit hole is for completeness and historical context.

Pro tip: When chatting with another Bitcoiner about a payment, confirm the unit before you send. "10k sats" and "0.0001 BTC" are the same amount; "10,000 sats" and "0.001 BTC" differ by 10x. The shared cultural language has converged on sats for small and BTC for large, but mismatches happen. Always verify.