Internal API calculations are performed using as many decimal places as necessary depending upon the precision of the currency in question, but displayed values are sometimes rounded/truncated to achieve a usable value or for formatting purposes.

For example, Bitcoin (BTC) calculations use up to 10 decimal places (the maximum usable precision for BTC is 8 places), but are sometimes displayed using only 5 decimal places. Similarly, US Dollar (USD) calculations use up to 4 decimal places (the maximum usable precision for USD is of course 2 places), but are often displayed using only 2 decimal places.

The REST API Assets endpoint can be used to determine the maximum decimal precisions for individual currencies:

As shown, the Assets endpoint provides the calculation decimal precisions via the decimals fields, and provides the display decimal precisions via the display_decimals fields.

Matching local values with API values

Values derived from local calculations (such as calculating balance changes from a trade's price and volume) often have more decimal places than required, and need to be rounded/truncated to match the values provided by the API.

For example, a SHIB/USD order to buy 50,123 SHIB at $0.00002901 results in a trade worth $1.45406823 (50,123 x 0.00002901 = 1.45406823), but the REST API Ledgers endpoint shows that the USD balance decreased by a smaller precision value of $1.4541:

The solution to this type of decimal precision discrepancy is to round/truncate local values to match the decimal precision provided by the REST API Assets endpoint.

Continuing the SHIB/USD example, the Assets endpoint indicates a USD calculation precision of 4 (see the previous section above), hence the locally calculated value of $1.45406823 should also be rounded/truncated to a decimal precision of 4:

As shown, by rounding/truncating to the appropriate decimal precision, the final value of $1.4541 corresponds exactly to the value provided by the Ledgers endpoint, allowing local values to be matched with API values successfully.