Deck stair layout

Deck Stair Stringer Calculator

Plan deck stairs from the total rise. Enter the height from the finished deck surface to the finished landing, then estimate risers, treads, total run, stair angle, stringer length, and stringer count.

Recommended layout 6 risers 42 in total rise with 7 in risers and 5 treads.
Stair height

Measure finished surface to finished surface. If your landing will get pavers, decking, or a pad, include that finished height.

Treads and stringers

Use the tread depth required for your decking and code. Many deck stairs use about 10 to 11 inches of run per tread.

How to use this stair stringer calculator

  1. Measure the total rise from the top of the finished deck to the top of the finished landing.
  2. Choose a target riser height. The calculator adjusts the riser count so each riser stays at or below your maximum.
  3. Enter the tread depth you plan to use. This gives the total run and stair angle.
  4. Enter stair width and stringer spacing to estimate how many stringers to cut.

Before cutting lumber, confirm your local rules for maximum riser height, minimum tread depth, nosing, landing size, guards, and handrails. Small differences in finished deck boards or landing height can change the first and last step.

Deck stair stringer FAQ

Why are there usually fewer treads than risers?

When the deck surface is the top walking surface, it acts like the final tread. That means a stair layout with 6 risers typically has 5 lower treads.

Should I round riser height up or down?

Do not round individual risers casually. Divide the exact total rise by the number of risers so every riser is as even as possible, then verify the result is allowed by local code.

What size board is used for stair stringers?

Many deck stair stringers are cut from 2×12 lumber, but the right material and allowable notching depend on span, stair width, loads, and local requirements.