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Concrete steps calculator
Measure the total rise from the ground to the top, and get how many steps it takes, the exact riser height, the run, and the concrete and bags to pour them, checked against Pennsylvania’s stair rule or the IRC.
Pennsylvania’s code (34 Pa. Code § 403.21) allows risers up to 8 1/4 in. with treads of at least 9 in. The model IRC caps risers at 7 3/4 in. with 10 in. treads. The same rise can need a different number of steps under each, so the calculator shows both.
Total rise: from the ground or walk where the bottom step sits, straight up to the top surface (porch, slab or door landing). Measure with a level and tape, not off the house.
Leave the landing at 0 if the steps run up to an existing porch or slab. If you’re pouring a new landing with the steps, enter its depth; the IRC calls for landings at least 36 in. deep in the direction of travel (R311.7.6).
Check the highlighted box: the rise, tread depth and width need to be greater than zero, the landing 0 or more, and waste from 0 to 50%.
The stair rules in the calculator
| Rule | Pennsylvania UCC | IRC model code |
|---|---|---|
| Maximum riser height | 8 1/4 in. | 7 3/4 in. |
| Minimum tread depth | 9 in. | 10 in. |
| Variation within a flight | Risers within 3/8 in.; treads within 3/8 in. | Risers within 3/8 in.; treads within 3/8 in. |
| Nosing | Treads may project up to 1 1/2 in. with solid risers | 3/4 to 1 1/4 in., not required with treads of 11 in. or more |
| Code section | 34 Pa. Code § 403.21(a)(7)(ii) | R311.7.5.1, R311.7.5.2, R311.7.5.3 |
Pennsylvania measures the riser vertically between the leading edges of adjacent treads, and the tread from nosing to nosing. Pennsylvania’s 8 1/4 and 9 in. limits come from state law: Penn State’s PHRC lists Act 13 of 2004 (stairway tread and riser requirements) among the statutory amendments in its 2021 PA UCC update. Whether a particular set of yard steps needs a permit is up to your municipality’s code official, so call before you form.
How it works
Risers = total rise ÷ the maximum riser, rounded up to a whole number. Riser height = total rise ÷ risers, so every riser is the same. Treads = risers − 1, because the top riser steps onto the porch or landing.
Total run = treads × tread depth, plus any new landing. That’s how far the steps stick out from the porch or wall, so check it against the walk or driveway before you dig.
Solid steps on grade: width × riser × tread × (1 + 2 + … + treads), plus width × landing depth × total rise. Cubic feet ÷ 27 = cubic yards. Bags = cubic feet ÷ the bag’s yield: 0.60 cu ft per 80 lb, 0.45 per 60 lb and 0.30 per 40 lb, from Quikrete.
24 in. rise, Pennsylvania rule: 24 ÷ 8.25 = 2.9 → 3 risers · 24 ÷ 3 = 8 in. each · 2 treads
11 in. treads: run = 2 × 11 = 22 in. · 4 ft wide: 4 × (8/12) × (11/12) × (1 + 2) = 7.33 cu ft
Plus 10%: 8.07 cu ft = 0.30 cu yd · 8.07 ÷ 0.60 = 13.4 → 14 bags of 80 lb
Same rise under the IRC: 24 ÷ 7.75 = 3.1 → 4 risers of 6 in. · 3 treads · 33 in. run · 11.0 cu ft
The concrete is for solid steps poured on grade. It doesn’t include footings, a stone base or rebar; where steps need footings, size them with the footing calculator and your local frost depth.
Related: the concrete calculator for slabs and piers, the slope calculator, and a real front walkway plan with steps for a 19 in. drop.
Questions
What is the maximum step height in Pennsylvania?
8 1/4 inches. Pennsylvania’s Uniform Construction Code, 34 Pa. Code § 403.21, sets the maximum riser height for residential stairs at 8 1/4 inches and the minimum tread depth at 9 inches, measured nosing to nosing. Within one flight, risers can’t vary by more than 3/8 inch, and the deepest tread can’t exceed the shallowest by more than 3/8 inch.
What does the IRC allow for stair risers and treads?
The model International Residential Code limits risers to 7 3/4 inches and requires treads of at least 10 inches (sections R311.7.5.1 and R311.7.5.2), with the same 3/8 inch variation limit. It also calls for a nosing of 3/4 to 1 1/4 inches unless the tread is at least 11 inches deep. Pennsylvania replaces the riser and tread limits with its own 8 1/4 and 9 inch rule.
How many steps do I need for a 24 inch rise?
Under Pennsylvania’s 8 1/4 inch limit, 24 inches takes 3 risers of exactly 8 inches, with 2 treads between the ground and the top. Under the IRC’s 7 3/4 inch limit it takes 4 risers of 6 inches and 3 treads. With 11 inch treads, that’s a run of 22 or 33 inches.
How much concrete do I need for 3 steps?
For a 24 inch rise built to Pennsylvania’s limit (3 risers of 8 inches, 2 treads of 11 inches) and 4 feet wide, solid steps on grade take about 7.3 cubic feet of concrete. With 10% extra that’s 8.1 cubic feet, or 14 bags of 80 lb mix at Quikrete’s 0.60 cubic feet per bag.
Do concrete steps need a handrail?
Under the IRC, handrails are required on at least one side of a stairway with four or more risers (section R311.7.8). A set of steps with three risers or fewer doesn’t trigger that rule, but check with your municipality’s code office for steps that serve a door.
How wide do steps have to be?
Pennsylvania’s code says stairways may not be less than 3 feet in clear width, with 6 feet 8 inches of clear headroom over the whole run. Handrails may project up to 3 1/2 inches into that width on each side.
Sources: 34 Pa. Code § 403.21, Uniform Construction Code (via Cornell LII): (a)(7)(ii)(A) maximum riser 8 1/4 in., no more than 3/8 in. variation, measured between leading edges of adjacent treads; (B) minimum tread 9 in., nosing to nosing; (C) tread variation 3/8 in.; (D) uniform projection up to 1 1/2 in. with solid risers; (E) 3 ft minimum clear width and 6 ft 8 in. headroom; (F) handrails may project 3 1/2 in.; City of Boise, IRC Code Handout #437, Treads and Risers, Feb. 2022 (R311.7.5.1 riser not more than 7 3/4 in.; R311.7.5.2 tread not less than 10 in.; 3/8 in. variation; R311.7.5.3 nosing 3/4 to 1 1/4 in., not required where treads are 11 in. or more); MyBuildingPermit.com Construction Tip Sheet 01, Basic Stairs, 2021 IRC (R311.7.8 handrail on at least one side with four or more risers; R311.7.6 landings at least 36 in. in the direction of travel); Penn State PHRC, 2021 PA UCC Residential Code Update webinar handout (Act 13 of 2004, stairway tread and riser requirements, listed among statutory amendments); Quikrete Concrete Mix No. 1101 data sheet (yields: 40 lb 0.30 cu ft, 60 lb 0.45 cu ft, 80 lb 0.60 cu ft); Quikrete calculator (yields approximate, no allowance for uneven substrate or waste). 1 cu yd = 27 cu ft. Checked Nov 8, 2026.
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