Tools · Hardscape
Steps on a slope calculator: how many outdoor steps, how tall, how deep
Garden steps that feel wrong usually break one rule: two risers plus one tread should add up to 26 in. Enter how much your slope rises and how far it runs, and get the number of steps, the riser and tread that fit, and a stake-out table for the layout.
Divide the rise into steps of about 6 in., and make each tread 26 in. minus two risers: 6 in. risers get 14 in. treads, 5½ in. risers get 15 in. treads. The top grade is the last tread, so a 30 in. rise is 5 risers, 4 treads and 4 ft 8 in. of run. Checked Nov. 13, 2026.
Landscape steps calculator
Rise: run a level string from the top grade out over the bottom step location and measure down to the ground. Run: the length of that string, from where the top step will sit to where the bottom step will start.
| Step | Top above bottom grade | Riser face from first riser |
|---|
Built on the 2R + T = 26 in. rule from University of Wisconsin-Extension, with risers kept between 4 and 7 in. and treads of at least 11 in., the ADA stair limits. Steps to a house door or deck fall under the building code; use our concrete steps calculator for those.
Comfortable riser and tread pairs
| Riser | Tread | Feels like |
|---|---|---|
| 4 in. | 18 in. | Long, strolling steps on a gentle bank |
| 5 in. | 16 in. | Relaxed garden steps |
| 5½ in. | 15 in. | One of the two most common outdoor pairs |
| 6 in. | 14 in. | The other common pair |
| 6½ in. | 13 in. | Steeper bank, still easy |
| 7 in. | 12 in. | Steepest pair inside the ADA riser limit |
Every pair adds to 26 in. using two risers plus one tread (UW-Extension). Keep every riser and tread in the flight the same; the residential code allows only 3/8 in. of variation (IRC R311.7.5).
How it works
Risers = total rise ÷ 6, rounded, kept between 4 and 7 in. tall. Riser height = rise ÷ risers.
Tread = 26 − 2 × riser height. Treads = risers − 1, because the top grade is the last tread.
Run needed = treads × tread depth. If your run is shorter, the calculator tries taller risers, up to 7 in.; if it’s longer, the extra goes to landings or a sloped walk.
Stake-out: riser k tops out at k × riser height above the bottom grade, and its face sits (k − 1) × tread from the face of the first riser.
Before you dig
A step or two is easy to miss. UW-Extension says a set of steps should have at least three risers, or stand out with material or lighting (G1923).
Pitch each tread toward the front so water runs off, but keep it under 1:48, about ¼ in. per foot (ADA 504.4).
Uneven risers trip people. Set each riser to the same height and adjust the base under it, not the tread thickness.
Handrails make outdoor steps safer, especially in winter (UW-Extension).
Questions
How do you figure steps on a slope?
Measure the total rise from the bottom grade to the top grade and the horizontal run between them. Divide the rise into equal risers of about 6 in., then size the tread so two risers plus one tread equal 26 in., the long-standing outdoor rule University of Wisconsin-Extension cites. The top grade acts as the last tread, so there’s one fewer tread than risers.
What is a comfortable rise and run for outdoor steps?
The most common outdoor combinations are 5½ in. risers with 15 in. treads and 6 in. risers with 14 in. treads. Both add up to 26 in. using two risers plus one tread.
How tall can an outdoor step be?
For public stairs the ADA Standards allow risers of 4 to 7 in. with treads at least 11 in. deep. Stairs governed by the residential building code, like steps to a house door or deck, can go to 7¾ in. with 10 in. treads. Garden steps usually run gentler: 5½ and 6 in. risers are the most common outdoor sizes.
What if my slope is too long for steps?
Use the extra run for landings, or a gently sloped walk between groups of steps. University of Wisconsin-Extension recommends steps once a walk slopes more than 6%, so a flatter run can stay a walk.
What if my slope is too short and steep?
Comfortable steps need about 12 in. of run for every 7 in. of rise. If the run isn’t there, start the bottom step farther out, turn the steps with a landing, or hold the grade with a retaining wall and put the steps through it.
Sources: University of Wisconsin-Extension, Landscape Structures (G1923, rev. 5/10/2010): two risers plus one tread = 26 in.; 5½ in. risers with 15 in. treads or 6 in. with 14 in.; at least three risers; steps where ground slopes more than 6%; U.S. Access Board, 2010 ADA Standards § 504.2 (risers 4 to 7 in., treads 11 in. minimum, uniform) and § 504.4 exception (tread slope up to 1:48); City of Boise, IRC Code Handout #437, Treads and Risers (R311.7.5: riser 7¾ in. max, tread 10 in. min, 3/8 in. variation). Checked Nov. 13, 2026.
Groundwork Design Co. · designed by builders
Get the steps drawn before you dig
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See the steps planAll free calculatorsAlso: retaining wall steps, concrete steps calculator, slope calculator, gravel compaction calculator.
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