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Stair calculator

Work out the number of steps and the exact riser height from a total rise.

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Need Number of steps, Actual riser height (cm)? The Stair calculator derives it from Total rise (cm), Target riser height (cm) in one step. For instance, with Total rise (cm) = 280 and Target riser height (cm) = 17 it returns Number of steps = 16 and Actual riser height (cm) = 17.5.

How to use it

  1. Enter your values: Total rise (cm), Target riser height (cm).
  2. Read the result instantly: Number of steps, Actual riser height (cm).

Frequently asked questions

How does the Stair calculator work?

It takes Total rise (cm) and Target riser height (cm) and derives Number of steps and Actual riser height (cm) from them. The calculation is live as you type, so the result updates on every change.

Which values does the calculator ask for?

2 values: Total rise (cm) and Target riser height (cm). Nothing else is required — no account, no file upload.

What does a typical calculation look like?

With Total rise (cm) = 280 and Target riser height (cm) = 17, the calculator returns Number of steps = 16 and Actual riser height (cm) = 17.5. Those figures come from running this exact tool, so you can reproduce them by entering the same values.

How much does the result change with different inputs?

It moves a lot. Using Total rise (cm) = 308 and Target riser height (cm) = 18.7 instead, Actual riser height (cm) goes from 17.5 to 19.25 — which is why it is worth testing a few scenarios rather than trusting a single figure.

What does it give for smaller values?

Scaled down to Total rise (cm) = 252 and Target riser height (cm) = 15.3, Actual riser height (cm) comes out at 15.75. The relationship is worth checking at both ends before you rely on a single result.

When would I actually use this?

Buying the right amount at the merchant: how many tiles, how much paint, how many bags of concrete, and what it all comes to.

What is the most common mistake?

Ordering the exact calculated quantity. Every material loses some of itself between the pallet and the finished job — offcuts, breakage, a bag that sets, a coat that soaks in further than the datasheet says — so add the allowance yours asks for, and order it in one delivery: a second batch rarely matches the first.

How accurate is it, and what are the limits?

Estimate only — confirm quantities with your supplier.

What is the difference between the Stair calculator and the Conduit fill calculator (NEC)?

This one returns Number of steps and Actual riser height (cm); the Conduit fill calculator (NEC) returns Conduit fill and NEC maximum fill. That is the whole difference — open the one whose figure you need.

Is there a tool for the next step?

Deck stain calculator is the closest one after this: How much stain a deck needs: the surface area of the boards, the railing and the stairs, divided by the coverage of your stain — which drops for solid stains and for rough or weathered wood — times the number of coats. Enter dimensions and it returns the gallons and, optionally, the cost.

Further reading

All guides →
How-toHow to Calculate a Staircase: Risers, Treads and the Rule That Ties Them TogetherA 110 in rise divided by a 7 in target gives 15.7 risers. You round to 16 and divide again, landing on 6 7/8 in. Here is the whole method, and why the building codes do not agree with each other.How-toSlope, Grade, Degrees and Ratio: How to Calculate Each and Convert Between ThemA 100 percent grade is 45 degrees, not vertical. Percent is rise ÷ run × 100, the angle is the arctangent of the same fraction, and the two are not proportional. Here is the conversion table and the three ways people get it wrong.How-toHow Much Concrete Do You Need?Concrete is measured by volume: length × width × depth. Here's how to work out cubic metres, add for waste, and choose bags or ready-mix.How-toHow Many Wall Studs Do I Need? Framing by Spacing and LengthCount the studs a wall needs from its length and stud spacing, then add for corners, openings and end studs so nothing is missing on framing day.How-toHow Many Concrete Blocks Do I Need? Blocks, Mortar and WasteWork out how many concrete blocks a wall needs from its area, add mortar and a waste allowance, and avoid a second trip to the yard.How-toHow Many Bricks Do I Need? Calculate Bricks Per WallEstimate bricks for any wall from its area, a per-square-foot brick count, and a waste allowance — so you buy once and avoid a second trip.