Stair Calculator
Work out a staircase — from the total rise and your riser height — in steps, actual riser, total run and angle.
Stairs are a division problem with a rule: every riser must be equal. This calculator divides the rise into equal steps, then gives you the run and the angle.
Enter the rise; the staircase follows. This is a planning estimate — a professional must confirm the design.
Your results
Enter your measurements and press Calculate.
Quantities are rounded up to whole tiles, planks, boxes or bags, after the wastage allowance. Cost appears only when you enter a price.
Formula
All lengths are converted to a single unit before the calculation: 1 ft = 0.3048 m, 1 in = 25.4 mm, 1 ft² = 0.09290304 m², 1 yd² = 9 ft². Material quantities are rounded up — you cannot buy part of a tile, plank or bag.
How to use this calculator
- Enter the total rise (floor to floor).
- Enter your desired riser height and tread depth.
- Read the step count, the actual riser, the total run and the angle.
Worked example
| Total rise | 2.8 m = 2,800 mm |
|---|---|
| Desired riser | 175 mm |
| Steps | ceil(2,800 ÷ 175) = 16 steps |
| Actual riser | 2,800 ÷ 16 = 175 mm |
| Total run | (16 − 1) × 250 mm = 3.75 m |
| Angle | atan(2,800 ÷ 3,750) = 36.75° |
Check it by hand: every step above uses the formula in the box. If your numbers match the example inputs but the calculator gives a different answer, please report it via the contact page.
Frequently asked questions
How many steps do I need?
Divide the total rise by your riser height and round up — then divide the rise by the step count to get the actual riser. A 2.8 m rise at 175 mm needs 16 steps.
What is a comfortable riser height?
Typically 150–200 mm. Lower is easier to climb but takes more steps and more run; higher is steeper. This calculator keeps every riser equal — never mix riser heights on one flight.
What is the total run?
The horizontal length the stairs take: (steps − 1) × tread depth. The top step is the floor itself, so there is one fewer tread than steps.
Is this a substitute for building design?
No. This is a geometry calculation for planning. Stair geometry, accessibility and building-code compliance vary by location — see the safety notice. A professional must confirm the design.
Related calculators
Estimates only. Results are for planning. Measure twice, confirm box coverage and tile sizes on the packaging you buy, and follow the manufacturer's instructions. See the disclaimer.