Free Tool
Free stair calculator
Enter your total rise and get the number of steps, the exact riser height, the treads, and the total run. Free, no signup.
Finished floor to finished floor
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Even risers, every time
The whole trick to a comfortable, code-legal stair is that every riser is the same height. Get that wrong and the odd step at the top is the one people trip on.
Enter the total rise, floor to floor, and a target riser height around 7 to 7.75 inches. The calculator rounds to a whole number of steps, then divides back to give you the exact riser height to lay out. It also gives you the treads, which are always one fewer than the risers, and the total run so you know how far the stair projects.
Set the tread depth for the feel you want. A deeper tread is easier to climb but eats more floor. Most codes want at least 10 inches of tread and cap the riser near 7.75, so confirm your local numbers before you cut the stringers.
With the layout set, mark the stringers, cut, and check the first step against your riser height before you run the rest.
Stair Calculator questions
How do I calculate stairs?
Divide the total rise by a comfortable riser height, round to a whole number of steps, then divide the rise by that number for the exact riser. The calculator does it and gives you treads and run too.
Why is there one fewer tread than riser?
The top floor is the last step up, so it counts as a riser but needs no tread. A stair with 14 risers has 13 treads.
What is a comfortable riser height?
Around 7 to 7.75 inches for most stairs. Codes usually cap it near 7.75, so check yours.
Is this really free?
Yes. No email, no signup, and nothing you type leaves your browser.
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Disclaimer: These free tools and templates are provided for general information and estimating purposes only. All results — including quantities, material and cost estimates, load, sizing, and span figures, scores, and any guidance or warnings — are rough approximations that may not fit your specific project, site conditions, local building codes, or current prices. They are not engineering, architectural, structural, legal, financial, or other professional advice, and are not a substitute for a licensed engineer, architect, contractor, or other qualified professional. Always confirm quantities, sizing, and structural, electrical, mechanical, and code requirements with a licensed professional and your local authority having jurisdiction before purchasing materials or performing any work. Werx makes no warranty as to accuracy and accepts no liability for any decision made using these tools. Use at your own risk. See our Terms of Service.