Stair Calculator
Estimate risers, treads and stringer length for any staircase.
Stair layout starts with total rise: divide the rise by a target riser height of about 7 inches, then round to a whole number of risers. The number of treads equals the number of risers minus one. Keep risers between 7 and 7.75 inches and treads between 10 and 11 inches so that 2 × riser + tread is close to 25 inches. Enter your total rise and run for a complete stringer layout.
Risers
14
7.71 in each
Total run
130
13 treads
Stringer
169.01
in (14.08 ft)
Save this project
Sign in to save calculations to your dashboard.
Download your PDF report & project guide
Your results and inputs, a printable shopping list, a step-by-step guide and pro tips — in one PDF.
Planning a whole project?
Get every calculator, a full shopping list and a budget template for:
Recommended tools & materials
Handy picks for this project on Amazon.
Speed Square
Fast angle and rafter layout
View on Amazon →
Framing Nailer
Drive framing nails in seconds
View on Amazon →
Construction Screws
Structural, coated, no pilot hole
View on Amazon →
25 ft Tape Measure
Durable, easy-to-read blade
View on Amazon →
As an Amazon Associate, MaterialCalc earns from qualifying purchases.
How does the stair calculator work?
Divide total rise by the maximum riser height (IBC 7.75 in) and round up to get the number of risers. Riser height = rise ÷ risers. Treads = risers − 1. Total run = treads × tread depth. Stringer = √(rise² + run²).
Which guide explains this in more depth?
- Riser-and-tread math plus 2026 material prices for a full stair build. Read the stair calculator cost breakdown guide for the full worked example.
What else do people ask about this calculator?
What is the maximum stair riser height?
IBC allows 7.75 in max; IRC (residential) allows 7.875 in. Minimum tread depth is 10 in (11 in for IBC commercial).
How long is a stair stringer?
For a 108 in rise and a 10 in tread, stringer length is √(108² + 130²) ≈ 169 in (14.1 ft). Order 16 ft stringers.
Which related calculators should I use next?
All calculators
Gear Up for Your Stair Build
These tools and fasteners help you lay out, cut, and assemble stair stringers accurately.
DEWALT Circular Saw
Search on Amazon →
BOSTITCH Framing Nailer
Search on Amazon →
Simpson Structural Screws
Search on Amazon →
Paid links: as an Amazon Associate, MaterialCalc earns from qualifying purchases.