Satoshi (unit)

The term "satoshi" in use on a message board

The satoshi is currently the smallest unit of the bitcoin currency recorded on the block chain. It is a one hundred millionth of a single bitcoin (0.00000001 BTC). The unit has been named in collective homage to the original creator of Bitcoin, Satoshi Nakamoto.

All amounts in the block chain are denominated in satoshi before being converted for display. The source code also uses satoshi when specifying an amount of bitcoin. When displaying an extremely fine fraction of a bitcoin, such as when calculating fee per byte or a faucet reward, the amount is displayed in satoshi for readability.

Although the satoshi is the finest amount that can be recorded in the block chain, payment channels may need to make very granular payments and so are sometimes denominated in millisatoshi, which are one hundred billionths of a single bitcoin.

In January 2018, 1 Euro cent is worth approximately 83 satoshi.

History

The value of a bitcoin in satoshi was decided by Satoshi Nakamoto to be 100 million no later than November 2008.

On November 15, 2010, ribuck proposed that the one hundredth of a bitcoin (0.01 BTC) be called a Satoshi. Four months later he instead suggested that the one hundred millionth unit be called an austrian or a satoshi. The name satoshi caught on, and was widely adopted thereafter.

In December 2017, BIP-176 also proposed "Bits" be used as a standard term for 100 (one hundred) satoshis or 1/1,000,000 (one one-millionth) of a bitcoin.

Usage

Plural

Traditionally, the plural form has been simply satoshi, but the term satoshis is also popular and equally correct. If the plural form were to follow the rules of Japanese grammar, it may be pronounced as satoshisa, or simply satoshi.

Symbol

Satoshi is often abbreviated to sat or s, although no currency symbol has been widely adopted. There are various proposed symbols:

Symbol	Explanation
	Reminiscent of the Japanese aesthetic, the closest character being 丰 meaning: "Bountiful - abundant, lush, bountiful, plenty, luxurious growth of grass" which suggests vasts amount of Satoshi are still left to mine. This symbol has been adopted by multiple Bitcoin services including satoshilabs.com (Trezor), SatoshiCap.net, pricedinbitcoin21.com, Thunderhub.io, bitcoinicons.com, thebitcoinmachines.com, and many more.
里	In Japanese names, this character can (rarely) be read "satoshi". It is an uncommon Chinese/Japanese character on its own, and an infrequent radical (kangxi #166). It can be seen as a radical in the common kanji 理 and 量, used in meaningful words like: 理想 (ideals), 理論 (theory), 理性 (reason), 理科 (science), and 量 (quantity). "Satoshi" is a rare reading; more commonly it is read as "ri" or "sato".
シ	A Japanese katakana representing the syllable "shi". Note that this character is extremely common in Japanese, so it could cause confusion. Also, it can mean "death" in Japanese and Chinese.
㋛	As above, but circled to distinguish it from the katakana.
し	As above, but this is the hiragana instead of the katakana. This is even more common than シ in Japanese writing, however.
サ	A Japanese katakana representing the syllable "sa". Maybe it looks more reminiscent of a currency symbol than others. Note that this character is extremely common in Japanese, so it could cause confusion.