The step attribute is a number that specifies the granularity that the value must adhere to or the keyword any. It is valid for the numeric input types, including the date, month, week, time, datetime-local, number and range types.

The step sets the stepping interval when clicking up and down spinner buttons, moving a slider left and right on a range, and validating the different date types. If not explicitly included, step defaults to 1 for number and range, and 1 unit type (minute, week, month, day) for the date/time input types. The value must be a positive number - integer or float — or the special value any, which means no stepping is implied and any value is allowed (barring other constraints, such as min and max).

Only values which are a whole number of steps from the step base are valid. The step base is min if specified, value otherwise, or 0 if neither is provided (except for week, which has a default step base of −259,200,000, representing the start of week 1970-W01).

Syntax

If any is not explicitly set, valid values for the number, date/time input types, and range input types are equal to the basis for stepping - the min value and increments of the step value, up to the max value, if specified. The following example results in any even integer, 10 or greater, being valid:

<input type="number" min="10" step="2" />

If step is omitted, any integer is valid but floats like 4.2 are not valid as step defaults to 1. For 4.2 to be valid:

• either step would have to be set to any, 0.1, or 0.2,
• or the min value would have to be a number ending in .2, such as 0.2, 1.2, or -5.2.

Examples

min impact on step

The value of min defines valid values, even if the step attribute is not included. This is because step defaults to 1 for the number input type.

In this example, we add a big red border around invalid inputs:

input:invalid {
  border: solid red 3px;
}

We then define an input with a minimum value of 1.2 and a step value of 2:

<input id="myNumber" name="myNumber" type="number" step="2" min="1.2" />

Valid values include 1.2, 3.2, 5.2, 7.2, 9.2, 11.2, and so on. Only floats with an odd-numbered integer part and a decimal part of .2 are valid. The number spinner, if present, generates valid float values of 1.2 and greater, in increments of 2.

See Client-side validation and stepMismatch for more information.

Accessibility concerns

Provide instructions to help users understand how to complete the form and use individual form controls. Indicate any required and optional input, data formats, and other relevant information. When using the min attribute, ensure this minimum requirement is understood by the user. Providing instructions within the <label> may be sufficient. If providing instructions outside of labels, which allows more flexible positioning and design, consider using aria-labelledby or aria-describedby.

Specifications

Browser compatibility

See also

• max
• min
• Constraint validation
• Form validation
• validityState.stepMismatch
• :out-of-range
• <input>
• date, month, week, time, datetime-local, number and range types, and the <meter>