Free stair calculator
Lay out your deck stair stringers
Enter your total rise. You get the number of risers, the boards to buy, and printable directions for marking and cutting your stringers (the notched boards that hold up the treads).
Deck surface down to where the stairs land. Type 43 1/2 or 3' 7-1/2"
A riser is one step up, counting the step onto the deck. Fewer risers, taller risers.
Front of one tread to the front of the next.
36" is the code minimum.
Enter your total rise to see the layout.
Your stair layout
Mark and cut your stringer, step by step
- Tape measure and pencil
- Framing square (the large L-shaped ruler)
- Stair gauges, or a straight scrap of wood and 2 clamps
- Circular saw
- Handsaw or jigsaw
Based on the 2021 International Residential Code and the AWC DCA 6 deck guide. Your local building department has the final say.
Stringer size by number of treads
- Tread material
- Wood
- Stair width
- 36" (3 stringers)
- Tread depth (run)
- 10 1/2"
- Tread thickness
- 1"
- Nosing
- 1"
- Stringer stock
- 2x12
Every row uses these settings. Enter your total rise above for exact cuts, or pick a row to load its example.
| Stringer | Risers | Total rise it covers | Example rise | Riser height | Total run | Stringer length | Boards to buy |
|---|---|---|---|---|---|---|---|
| 1 tread | 2 | 8" to 15 1/2" | 11 3/4" | 5 7/8" | 10 1/2" | Build a box step or use solid blocks | |
| 2 treads | 3 | 15 1/2" to 23 1/4" | 19 3/8" | 6 7/16" (first 6 1/2") | 21" | 2' 0 1/8" | 2 × 8', cut in half |
| 3 treads | 4 | 23 1/4" to 2' 7" | 2' 3 1/8" | 6 13/16" (first 6 3/4", top 6 3/4") | 2' 7 1/2" | 3' 1" | 2 × 8', cut in half |
| 4 treads | 5 | 2' 7" to 3' 2 3/4" | 2' 10 7/8" | 7" (first 6 15/16", top 6 15/16") | 3' 6" | 4' 1 7/8" | 1 × 10', cut in half, + 1 × 8' |
| 5 treads | 6 | 3' 2 3/4" to 3' 10 1/2" | 3' 6 5/8" | 7 1/8" (first 7 1/16", top 7 1/16") | 4' 4 1/2" | 5' 2 7/8" | 1 × 12', cut in half, + 1 × 8' |
| 6 treads | 7 | 3' 10 1/2" to 4' 6 1/4" | 4' 2 3/8" | 7 3/16" (first 7 1/4") | 5' 3" | 6' 3 13/16" | 3 × 8' |
| 7 treads | 8 | 4' 6 1/4" to 5' 2" | 4' 10 1/8" | 7 1/4" (first 7 5/16", top 7 5/16") | 6' 1 1/2" | 7' 4 13/16" | 3 × 8' or 10' |
| 8 treads | 9 | 5' 2" to 5' 9 3/4" | 5' 5 7/8" | 7 5/16" (first 7 3/8") | 7' 0" | 8' 5 13/16" | 3 × 10' |
| 9 treads | 10 | 5' 9 3/4" to 6' 5 1/2" | 6' 1 5/8" | 7 3/8" (first 7 5/16", top 7 5/16") | 7' 10 1/2" | 9' 6 7/8" | 3 × 12' |
| 10 treads | 11 | 6' 5 1/2" to 7' 1 1/4" | 6' 9 3/8" | 7 3/8" (first 7 1/2", top 7 1/2") | 8' 9" | 10' 7 13/16" | 3 × 12' |
| 11 treads | 12 | 7' 1 1/4" to 7' 9" | 7' 5 1/8" | 7 7/16" (first 7 3/8", top 7 3/8") | 9' 7 1/2" | 11' 8 15/16" | 3 × 14' |
| 12 treads | 13 | 7' 9" to 8' 4 3/4" | 8' 0 7/8" | 7 7/16" (first 7 9/16", top 7 1/2") | 10' 6" | 12' 9 7/8" | 3 × 14' |
| 13 treads | 14 | 8' 4 3/4" to 9' 0 1/2" | 8' 8 5/8" | 7 1/2" (first 7 5/16", top 7 5/16") | 11' 4 1/2" | 13' 11 1/16" | 3 × 16' |
| 14 treads | 15 | 9' 0 1/2" to 9' 8 1/4" | 9' 4 3/8" | 7 1/2" (first 7 7/16", top 7 7/16") | 12' 3" | 15' 0 1/16" | 3 × 16' |
| 15 treads | 16 | 9' 8 1/4" to 10' 4" | 10' 0 1/8" | 7 1/2" (first 7 9/16", top 7 9/16") | 13' 1 1/2" | 16' 1" | 3 × 18' |
| 16 treads | 17 | 10' 4" to 10' 11 3/4" | 10' 7 7/8" | 7 1/2" (first 7 11/16", top 7 11/16") | 14' 0" | 17' 2" | 3 × 18' |
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