Stair Stringer Calculator

How long should my stair stringers be?

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Order this much at 10 ft long

42×12 stringers

Stringer spacing is a common choice and no table sets it. Check your deck or stair guide for the minimum throat, about 5 in is typical, and confirm with your building department.

7.71 in rise × 10.5 in runCut 7 ft 7 1/4 in, 4 stringers
Risers7
Unit rise7.71 in
Stringer cut length7 ft 7 1/4 in
Board to buy10 ft 2×12
Throat left in a 2×125.03 in

See how many 2×12 stringers to buy for a deck or basement stair, and how much wood is left after the cuts.

How it works

Each step is the square root of rise squared plus run squared. Multiply by risers for the cut length, then round up to a stock board.

Before you order

  • Crown side up. Sight each board and lay out on the straight edge.
  • Cut the notch corners with a handsaw so you do not overcut into the throat.
  • Lay out the first stringer, then trace it onto the rest.

Common questions

How many stringers does a 36 inch stair need?

Usually 3 stringers, one per side and one in the center.

How much wood should remain under the cuts?

About 5 inches is a common minimum. Check your deck or stair guide.