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Fractional Amounts

To maximize precision and efficiency, Account debits/credits and Transfer amounts are unsigned 128-bit integers. However, currencies are often denominated in fractional amounts.

To represent a fractional amount in TigerBeetle, map the smallest useful unit of the fractional currency to 1. Consider all amounts in TigerBeetle as a multiple of that unit.

Applications may rescale the integer amounts as necessary when rendering or interfacing with other systems. But when working with fractional amounts, calculations should be performed on the integers to avoid loss of precision due to e.g. floating-point approximations.

TigerBeetle stores information precisely and efficiently, while applications can still present fractional amounts to their users in a way that they are familiar with seeing them.

Asset Scale​

When the multiplier is a power of 10 (e.g. 10 ^ n), then the exponent n is referred to as an asset scale. For example, representing USD in cents uses an asset scale of 2.

Examples​

  • In USD, $1 = 100 cents. So for example,
    • The fractional amount $0.45 is represented as the integer 45.
    • The fractional amount $123.00 is represented as the integer 12300.
    • The fractional amount $123.45 is represented as the integer 12345.

Oversized Amounts​

The other direction works as well. If the smallest useful unit of a currency is 10,000,000 ¤, then it can be scaled down to the integer 1.

The 128-bit representation defines the precision, but not the scale.