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Siacoins

Siacoins are the primary currency of the Sia network. One siacoin is defined as 10^24 base currency units, known as "hastings." Other denominations use SI prefixes:

  • TS: terasia, 1 trillion SC
  • GS: gigasia, 1 billion SC
  • MS: megasia, 1 million SC
  • KS: kilosia, 1 thousand SC
  • SC: siacoin, 1 SC
  • mS: millisia, 10^-3 SC
  • uS: microsia, 10^-6 SC
  • nS: nanosia, 10^-9 SC
  • pS: picosia, 10^-12 SC
  • H: hasting, 10^-24 SC

Siacoins are used to fund File Contracts: renters buy storage with siacoins, and hosts are paid in siacoins. They are also the currency in which Siafund dividends are paid. Lastly, the Block reward and the Foundation subsidy are disbursed as siacoins.

Siacoin values are represented as a 128-bit integer number of hastings. This bounds the total supply to approximately 340 TS. Given that 60 KS are created in each block, this limit will not be reached for more than 100,000 years.

In v1

Currency values were encoded as an 8-byte length prefix, followed by a big-endian base-2 representation of the integer. This meant that currency values were effectively unbounded. Currency arithmetic was performed using arbitrary-precision integers, which were significantly slower than 128-bit fixed-point.