The Fixed package allows you to store and perform math on decimal numbers with a fixed scale (fixed no. of decimal places).

All amounts are stored as BigInts to allow precision math to be performed.

The features of Fixed are:

• Fixed uses a selectable fixed scale (no. of decimal places)
• Fixed provides a builtin formatter and parser Fixed.format(pattern)
• Full set of mathematical opertors.
• Fixed includes a convenience method Fixed.formatIntl(locale) which formats the number with the provided locale or the default locale if not provided.

Sponsors

Fixed is sponsored by OnePub, the Dart private package repository.

You can create a Fixed instance from a number of sources:

import 'package:fixed/fixed.dart';

void main() {
  final t1 = Fixed.fromNum(1, decimalDigits: 2); // 1.00
  final t2 = Fixed.fromNum(1, decimalDigits: 3); // 1.000

  final add = t1 + Fixed.ten;
  final multiply = t1 * t2;
  print(add); // 11.00
  print(multiply); // 1.00000

  final t3 = Fixed.parse('1.23356'); // decimalDigits: 5

  if (t1 == t2) { // true
    print(t1.format('0.##')); // 1.00
    print(t3.format('0.###')); // 1.233
  }
}

Numeric equality, ordering (compareTo and relational operators), and hash codes ignore differences in scale: Fixed.parse('1.0') and Fixed.parse('1.00') represent the same value and can be used interchangeably as map keys.

Parsing consumes the entire input and throws FixedParseException for invalid suffixes or input without digits. Fixed.tryParse returns null for invalid input. Whitespace is ignored, grouping separators are accepted, and invertSeparator: true swaps the decimal and grouping separators.

~/ truncates the quotient towards zero and retains the larger operand scale. For example, Fixed.parse('7.50') ~/ Fixed.parse('2.0') produces 3.00, and the corresponding remainder is 1.500.

divide(num) retains the original value's scale and rounds once, half away from zero. It interprets the divisor's decimal string representation without computing a floating-point reciprocal. For example, Fixed.parse('1.00').divide(3) produces 0.33. Zero and non-finite divisors throw FixedException. pow(0) returns one at the original scale, including scales above 20 decimal digits.

Full documentation can be found here.