Deck Stair Calculator
Enter the total rise from the deck surface to the landing and get an even riser height, tread count, and how many stringers the stair width needs.
Stairs & Stringers
Steps5
Actual riser7.20 in
Stringers (16" O.C.)4
Tread boards8
Material cost$152.00
Line total$152.00
Deckworks saves the math with the line item so your customer sees exactly how you priced it.
Get the free Deck Quote Checklist
A one-page checklist so you never forget footing depth, waste factor, or permit costs on a deck quote.
No spam. Unsubscribe any time.
How the math works
- 01Steps = total rise ÷ target riser height, rounded up.
- 02Actual riser = total rise ÷ steps — this is the number that must be equal on every step.
- 03Treads = steps − 1 when the deck surface is the top step.
- 04Stringers = stair width ÷ 1.5ft, plus one, with a minimum of two.
Common questions
What is the maximum riser height for deck stairs?
The IRC caps risers at 7.75in and requires the tallest and shortest riser in a flight to be within 3/8in of each other. Always round the step count up so the actual riser drops below your target.
How many stringers do I need?
Stringers at 16in on center is the common rule — a 4ft-wide stair typically needs four. Composite treads may require tighter spacing.
Other deck calculators
Deck Board Calculator
Enter your deck dimensions and board size to see how many decking boards you need, including a waste factor. The calculator shows the full math so you can drop it straight into a quote.
Deck Joist Calculator
Figure out how many joists your deck frame needs at 12, 16 or 24 inches on center, plus rim and band joists.
Deck Railing Calculator
Work out how many railing sections and posts you need for a run of deck railing, and what the material costs.
Deck Screw Calculator
Estimate how many deck screws and how many boxes you need for a given deck area.
Concrete Footing Calculator
Calculate the concrete volume for round deck footings and convert it to 60lb or 80lb bags.