Stair Riser & Tread Calculator

Estimate riser count, actual riser height, tread count, total run, and 2R+T from floor height.

GUIDE

How to use Stair Riser & Tread Calculator

Estimate riser count, actual riser height, tread count, total run, and 2R+T from floor height. The tool is available directly in your browser with no account required.

1. Enter the required value, text, or file in the tool above.
2. Adjust any available options and run the tool when needed.
3. Review the result and copy or download it if the tool provides that option.

DETAILS

Dividing floor height into equal risers

The calculator rounds floor height divided by a target riser to a whole number, then divides the height again to find the equal actual riser.

3,000 mm example

A 3,000 mm floor height with a 170 mm target gives 18 risers at about 166.67 mm each.

Good to know

Early planning only. Verify landings, finishes, structure, accessibility, egress, and local building-code limits before design or construction.

Frequently asked questions

Why are there fewer treads than risers?

For a single straight flight, the upper floor commonly acts as the final walking surface.

What is 2R+T?

It is a basic relationship between two riser heights and one tread depth used to compare stair proportions.

Related architecture tools

📐

Drawing Print Scale

Calculate print percentage and resulting drawing scale when paper size changes.

📏

Drawing Scale Length

Convert between drawing length and real-world length at common scales.

📈

Slope / Angle Converter

Convert slope percentage, angle, and 1:n gradient formats.

▧

Drawing Area & Pyeong

Convert measured drawing area into real square metres, pyeong, and square feet.

CAD Text Height

Calculate model-space CAD text height from printed text size and drawing scale.

↗

Ramp Length & Slope

Calculate ramp rise, horizontal run, sloped length, grade, and angle.