Stair Stringer Calculator
Estimate the steps, individual rise and run, stringer board lengths, wood board quantities, and total material budget for stairs.
Example Projects
Low-Rise Deck Steps
36" total rise (5 steps) · 36" wide deck stairs
High-Rise Deck Steps
96" total rise (14 steps) · 48" wide closed riser
Standard Basement Stairs
108" total rise (14 steps) · Closed risers
Gentle Patio Steps
30" total rise (5 steps) · 60" wide masonry look
Stair Layout View Results
Stair Layout
View Material & Cost Details
| Material Item | Needed Specs | Lumber Quantity | Cost |
|---|---|---|---|
| 2x12 Stringers | 0.00" | 0 sticks (0 ft) | $0.00 |
| Treads | 0 treads | 0 boards | $0.00 |
| Risers (Closed Faces) | N/A | 0 boards | $0.00 |
Stair Framing Formulas:
Everything behind the Stair Stringer Calculator
Formulas, reference charts, and detailed answers — expand any section you need.
How Many Steps Do I Need for My Stairs?
Step count depends entirely on total rise. Divide the vertical height by your target rise per step (7 to 7.75 inches is standard for most homes) and round to the nearest whole number. Rounding up gives a more comfortable, gentler step; rounding down gives a steeper step but takes up less horizontal space.
| Total Rise | Steps (at 7.5 in rise) |
|---|---|
| 48 in | 6 steps |
| 72 in | 10 steps |
| 96 in | 13 steps |
| 108 in | 14 steps |
Stair Stringer Calculator: How to Calculate Rise and Run
Total rise is the full vertical height the stairs need to climb, measured from finished floor to finished floor. To find the number of steps, divide total rise by a target individual rise (commonly 7 to 7.75 inches), then round to a whole number of steps. Divide total rise again by that step count to get the exact rise per step, since every step must be equal for the stairs to be safe and code-compliant.
Example: A total rise of 96 inches divided by a 7.5 inch target gives 12.8, rounded to 13 steps. Recalculating gives an exact rise of 7.38 inches per step.
Stair Stringer Length Calculator
Stringer length is the diagonal cut length of the board that supports the treads, calculated using the Pythagorean theorem on total rise and total run. A stringer is always longer than either the rise or the run alone since it spans the hypotenuse of the stair triangle.
Example: A staircase with a 96 inch total rise and 130 inch total run needs a stringer length of about 161 inches (roughly 13.4 feet), before adding extra for top and bottom cuts.
How Many Stringers Do I Need for Deck Stairs?
Stringer count depends on stair width and the span rating of your tread material. Most residential stairs under 36 inches wide use 2 stringers. Wider stairs, or stairs using composite decking with lower span ratings, typically require 3 stringers. Commercial or heavy load stairs may need 4 or more.
Stair Rise and Run Code Requirements
Most residential building codes cap maximum rise at 7.75 inches per step and require a minimum run (tread depth) of 10 inches, though exact figures vary by state and local jurisdiction. Consistency between steps matters as much as the individual measurements, since even a small variance between steps is a common cause of falls.