What is a comfortable stair riser height?

Most codes cap risers at about 7.75 inches; 7–7.5 inches feels comfortable for everyday use.

How many stringers do I need?

Plan a stringer at each end and one every 16 inches in between, so a 36 in wide stair uses three stringers.

Deck Stairs Calculator

Calculate stringers, risers and treads for deck stairs.

100% free to useNo sign-up requiredImperial & metric units

How do you calculate deck stairs?

Divide the total rise by a target riser height near 7.25 inches and round to a whole number of equal steps. A 36 inch rise gives 5 steps at 7.2 inches each, with 4 treads. Keep every riser within 3/8 inch of the others and use the 2R plus T rule near 25 inches for comfort.

Inputs

Total risein

Target riser heightin

Tread depthin

Stair widthft

Stringer spacing

Results

Number of Steps

Equal risers

Riser Height

7.2 in

Treads

Total Run

40 in

Stringers

Cut from 2x12

Tread Material

16 ft

Linear feet

Estimates update instantly as you type. Confirm against local code before ordering materials.

Stair geometry is where decks most often fail inspection. This calculator takes the total rise from the deck surface to the landing and your target riser height, then returns an equal number of steps, the exact riser height, the tread count, and the total run so your stringers fit the space.

Code limits riser height and requires risers to be uniform within a tight tolerance, so the calculator divides the rise into equal steps rather than leaving an odd last riser. Pair the riser and tread numbers against the common 2R + T rule of thumb for comfortable, code-friendly stairs.

How stair geometry is calculated

The total vertical height is divided into equal risers within a comfortable height range. The number of treads is one less than the number of risers, and total run comes from tread depth.

Steps = Total Rise ÷ Target Riser Height (rounded)

Common riser and tread combinations

Code-friendly stair geometry for typical deck heights.

Total rise	Steps	Riser height	Total run
24 in	3	8.0 in	20 in
36 in	5	7.2 in	40 in
48 in	7	6.9 in	60 in
60 in	8	7.5 in	70 in

Most codes cap riser height near 7.75 inches and require uniform risers within 3/8 inch.

How to use it

1Enter the total rise from grade to the deck surface in inches.
2Set your target riser height (7–7.75 in is comfortable).
3Set the tread depth (10–11 in is typical).
4Review the number of steps, exact riser height and total run.

Key terms explained

Total rise: The vertical distance from the upper deck surface to the lower landing or grade.
Riser: The vertical face of each step. Codes commonly cap it near 7.75 inches and require uniformity.
Tread: The horizontal stepping surface. Its depth affects comfort and total run.
Total run: The horizontal distance the stair occupies, which determines where the stringer lands.

Worked examples

Standard deck stair

A 36 in rise with 7.2 in risers gives 5 steps and a 40 in total run at 10 in treads.

Tall deck

A 60 in rise produces 8 risers at 7.5 in and a 70 in run at 10 in treads.

Pro tips from the field

1Keep every riser within 3/8 inch of the others; inspectors measure this directly.
2Check the total run against available space before cutting stringers, stairs eat more room than expected.
3Use the 2R + T rule near 25 inches for a comfortable stride.
4Account for the thickness of the tread material when setting your finished riser heights.

Common mistakes

Allowing risers to vary more than 3/8 inch between steps.
Forgetting that treads equal risers minus one.
Ignoring code limits on maximum riser height.

Where it gets used

Stringer layout

Get exact riser and tread numbers before marking and cutting stringers.

Inspection prep

Confirm uniform risers that meet local code limits.

Landing placement

Use total run to position the bottom landing or pad correctly.

Frequently asked questions