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Stair Stringer Calculator · Free calculator

Stair Stringer Calculator: 48" Total Rise

For 48" from finished floor to finished floor (4' 0"), you need 7 risers of 6-7/8" and 6 treads. With 10" treads the stairs run 5' 0" and each stringer is 6' 4-13/16" long — cut from a 8' 2x12.

Quick answer

Risers
7 × 6-7/8"
Treads (10")
6
Total run
5' 0"
Stringer length
6' 4-13/16"
2x12 stringers (36" wide)
3 × 8'
IRC
✓ Meets code

▍Stair Stringer Calculator

in
Tread depth (run)
in
Risers × height
7 × 6-7/8"
✓ Meets IRC (riser ≤ 7-3/4", tread ≥ 10")
4' 0"RUN 5' 0"
Treads
6
Total run
5' 0"
Stringer length
6' 4-13/16"
Angle
34.4°
2x12 stringers
3 × 8'
2R + T
23.71in

48" rise — tread depth options

TreadTotal runStringerAngle2R + TStock
10"5' 0"6' 4-13/16"34.4°23.718'
10-1/2"5' 3"6' 7-3/16"33.1°24.218'
11"5' 6"6' 9-5/8"31.9°24.718'
1' 0"6' 0"7' 2-9/16"29.7°25.7110'

48" rise — riser count options

IRC R311.7.5.1: riser height 7-3/4" max. Comfortable stairs land at 7"–7-1/2".

RisersRiser heightTreadsMeets IRC
68"5No — too tall
76-7/8"6Yes
86"7Yes
95-5/16"8Yes

How the math works

  1. Risers = 48" ÷ 7.75" max = 6.19 → round up to 7
  2. Riser height = 48" ÷ 7 = 6.8571" ≈ 6-7/8"
  3. Treads = risers − 1 = 6
  4. Total run = 6 × 10" = 5' 0"
  5. Stringer = √(48² + 60.0²) = 6' 4-13/16"

Subtract one tread thickness from the bottom riser of the stringer (drop the stringer) so the first step matches the rest.

Trade pro tips

  • Measure the 48" rise from finished floor to finished floor — add flooring and tread thickness to rough measurements.
  • Cut one stringer, test it in place, then trace it for the rest.
  • At 36" wide, use 3 stringers; at wider than 36", add one stringer per 16"–18".

Frequently asked questions

How many steps for a 48 inch rise?

7 risers (steps up) of 6-7/8" each, with 6 treads. That stays under the IRC maximum riser height of 7-3/4".

How long of a stringer do I need for a 48" rise?

6' 4-13/16" along the slope with 10" treads (total run 5' 0"). Buy 8' 2x12s to leave room for the top and bottom cuts.

What is the riser height for a 48" stair?

6.857" — about 6-7/8" on the tape. 2R + T = 23.71", outside the 24"–25" comfort range — consider adjusting tread depth.

What angle are 48" stairs?

34.4° with 10" treads. Residential stairs typically fall between 30° and 37°.