1Overview

The Decimal scalar type represents a decimal floating-point number with high precision. It is intended for scenarios where precise decimal representation is critical, such as financial calculations, monetary values, scientific measurements, or any domain where floating-point rounding errors are unacceptable.

Unlike the built-in Float scalar which uses binary floating-point representation (IEEE 754) and can introduce rounding errors in decimal calculations, Decimal provides exact decimal representation.

Note: JavaScript’s number type uses binary floating-point (IEEE 754 double precision) and cannot accurately represent all decimal values. For example, 0.1 + 0.2 in JavaScript does not equal 0.3 exactly. Client applications using JavaScript should handle Decimal values with care, potentially using libraries like decimal.js, big.js, or bignumber.js for precise decimal arithmetic.

2Recommended name

The recommended name for this scalar is Decimal.

3Result spec

A Decimal scalar must serialize to a numeric value representing the decimal number.

The serialized value is a standard numeric representation that can include:

• Optional leading sign (negative values)
• Integer and fractional components
• Standard decimal notation

4Input spec

A Decimal scalar accepts numeric values representing decimal numbers, both as GraphQL literals and as JSON input values.

Implementations should validate:

• Value is a valid number (not NaN or Infinity)
• Value is within the supported precision range of the implementation

mutation {
  processPayment(amount: 99.99, taxRate: 0.08) {
    total
  }
}

{
  "amount": 99.99
}

{
  "price": 1234567890.123456789
}

5References

• GraphQL Specification – Float — Built-in floating-point scalar type