Stair Calculator
Enter your total rise to get the stair layout: risers, riser height and total run.
Stair layout
How to calculate stairs
Stairs need equal risers. Divide the total rise by the max riser height and round up to get the number of risers, then divide the total rise by that number for the exact riser height. Treads are always one less than risers.
Formula: risers = total rise ÷ max riser height, rounded up, and riser height = total rise ÷ risers
Worked example: 105 inch rise, 10 inch treads
Risers: 105 ÷ 7.75 = 13.55, rounded up to 14 risers. Each riser: 105 ÷ 14 = 7.5 inches. Treads: 14 − 1 = 13 treads. Total run: 13 × 10 = 130 inches.
Keep risers equal
Uneven risers trip people. If your math gives uneven heights, adjust the riser count until every riser matches within a tiny fraction.
Common rises
Cost tips
Prices on this page are editable estimates, not quotes. Get 2 to 3 local quotes before you buy, and ask if delivery is included. Delivery, tax and waste can change the total a lot. Order a little extra for cuts and breakage, and confirm final quantities with your supplier or a qualified professional.
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Frequently asked questions
How many steps do I need for a 105 inch rise?
A 105 inch rise needs 14 risers at 7.5 inches each, with 13 treads and a total run of 130 inches at a 10 inch tread depth.
How tall should each step be?
Risers are usually 7 to 7.75 inches. Keep every riser the same height, or the stair feels unsafe.
How deep should treads be?
About 10 inches for comfortable stairs. Building codes usually need at least 10 inches.
Why is total run less than risers times tread depth?
There is one less tread than risers, because the top floor itself is the last step.
Does this follow building codes?
It follows common US rules, but always check your local code for riser height, tread depth and headroom.