What does this JSON Schema validate?

## The multipleOf Keyword The multipleOf keyword constrains a number to be an exact multiple of a given value. This is useful for enforcing decimal precision, step increments, and divisibility rules. ### Basic Syntax json { "type": "number", "multipleOf": 0.01 } This ensures the number has at most two decimal places. Values like 19.99, 100, and 0.5 pass, but 19.999 fails because it is not a multiple of 0.01. ### How the Example Schema Works The schema demonstrates three practical uses

Number multipleOf Validation in JSON Schema

Use the multipleOf keyword in JSON Schema to constrain numbers to specific increments. Validate currency precision, rotation angles, and batch sizes.

Number Constraints

JSON Schema

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "properties": {
    "price": {
      "type": "number",
      "multipleOf": 0.01,
      "minimum": 0
    },
    "angle": {
      "type": "number",
      "multipleOf": 90,
      "minimum": 0,
      "maximum": 360
    },
    "batchSize": {
      "type": "integer",
      "multipleOf": 10,
      "minimum": 10,
      "maximum": 1000
    }
  },
  "required": ["price"]
}

Test Data

{
  "price": 19.99,
  "angle": 270,
  "batchSize": 50
}

Detailed Explanation

The multipleOf Keyword

The multipleOf keyword constrains a number to be an exact multiple of a given value. This is useful for enforcing decimal precision, step increments, and divisibility rules.

Basic Syntax

{
  "type": "number",
  "multipleOf": 0.01
}

This ensures the number has at most two decimal places. Values like 19.99, 100, and 0.5 pass, but 19.999 fails because it is not a multiple of 0.01.

How the Example Schema Works

The schema demonstrates three practical uses of multipleOf:

price — multipleOf: 0.01 restricts values to two decimal places, matching standard currency precision. The value 19.99 passes (19.99 / 0.01 = 1999, a whole number). A value like 19.995 would fail.
angle — multipleOf: 90 with minimum: 0 and maximum: 360 accepts only right-angle rotations: 0, 90, 180, 270, and 360. The value 270 passes.
batchSize — multipleOf: 10 ensures batch sizes come in multiples of ten: 10, 20, 30, etc. Combined with minimum: 10 and maximum: 1000, the valid values range from 10 to 1000 in steps of 10. The value 50 passes.

Floating-Point Precision Warning

Because JSON numbers use IEEE 754 double-precision, multipleOf can produce unexpected results with certain decimal values. For example:

0.1 + 0.2 = 0.30000000000000004 (in IEEE 754)

Most well-implemented validators handle this by comparing with an epsilon tolerance, but some do not. When using multipleOf with decimal fractions, test your specific validator to confirm its behavior.

Common Patterns

Use case	multipleOf value	Effect
Currency (2 decimal places)	`0.01`	Rejects `9.999`
Whole numbers	`1`	Same as `type: "integer"`
Even numbers	`2`	Accepts 2, 4, 6, ...
Quarter hours	`15`	Accepts 0, 15, 30, 45
Percentage points	`0.1`	One decimal place

Combining with Range Constraints

Always combine multipleOf with minimum and/or maximum to fully constrain the value space. Without range limits, multipleOf: 10 accepts any multiple of 10, including negative values and extremely large numbers.

Use Case

Use multipleOf for pricing fields in e-commerce APIs, rotation and positioning values in graphics applications, batch size parameters in data processing endpoints, and time interval settings. It ensures values align with your application's precision requirements.

Try It — JSON Schema Validator

Open full tool →