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Free Stair Calculator
Calculate the number of steps, riser height, run and stringer length for a staircase.
What is the Stair Calculator?
Calculate the number of steps, riser height, run and stringer length for a staircase.
It divides the total rise by your preferred riser height, rounds to a whole number of steps, and recalculates the exact riser. Treads are one fewer than risers, the run is treads times tread depth, and the stringer is the diagonal of the rise and run.
Home and building jobs are easier to price when you know how much material you really need. A quick estimate also helps you avoid buying too little or too much.
How to use the Stair Calculator
Using the stair calculator takes a minute or two. Your entries are saved in this browser, so you can come back later and carry on.
Step 1
Enter the measurements of the area you are working on.
Step 2
Read the amount of material needed, including a waste allowance where relevant.
Step 3
Round up when you buy, and check the figures with your supplier.
Tips for better results
The 2 x riser + tread check is a comfort guide only. Stairs are regulated for riser height, tread depth, headroom and handrails, so follow your local building code and consult a licensed professional before building.
Add 5 to 10 percent for waste, cuts and mistakes.
Measure twice, order once, and check quantities with your supplier.
Privacy and where your data goes
Everything you type into the stair calculator stays on your own device. Zapxa does not receive your numbers or documents. If you clear your browser data, your saved entries will be removed, so download a PDF of anything you want to keep.
Frequently asked questions
Why are there fewer treads than risers?
The top riser meets the upper floor, which acts as the last tread. A staircase with 15 risers therefore has 14 treads.
What does the 2 x riser + tread rule mean?
It is a comfort guide where twice the riser plus the tread should land around 24 to 25 inches. Building codes set their own limits, so check yours.
Is the stair calculator free?
Yes. It is free to use with no signup, no watermark and no usage limits.
Is my data private?
Yes. Your inputs are processed in your browser and saved only in its local storage. They are not uploaded to our servers.
Does it work on mobile?
Yes. Zapxa works on phones, tablets and desktops. Use the print button or download a PDF to keep a copy.
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