Stair Riser Calculator

Calculating stair riser height requires dividing the total floor-to-floor vertical rise into an exact number of equal steps so that no single step is

Construction

Total Vertical Rise (Inches)

Finished floor-to-floor vertical distance (enter 0 if using feet/inches below)

Target Maximum Riser Height

Maximum allowed riser height per local planning guidelines (commonly 7.75 in)

Total Rise Feet (Optional)

Optional feet portion (e.g. enter 9 for 9 ft 6 in)

Total Rise Inches (Optional)

Optional inches portion paired with feet (e.g. 6 for 9 ft 6 in)

Formula & Methodology

Riser Count = Ceiling(Total Rise ÷ Max Riser Limit) Exact Riser Height = Total Rise ÷ Riser Count Cumulative Rise Check = Riser Count × Riser Height = Total Rise (Exact)

To prevent exceeding the allowable riser ceiling (commonly 7.75 inches for residential stairs), total vertical rise is divided by the target maximum, and the quotient is rounded up to the nearest whole integer. Dividing total rise by this integer count produces an exact, uniform riser height where every step is identical with zero remainder.

Exact Individual Riser Height

7.7143 in (14 Risers) in

Overview

Calculating stair riser height requires dividing the total floor-to-floor vertical rise into an exact number of equal steps so that no single step is taller or shorter than any other. Because even a quarter-inch height difference between steps creates a serious trip hazard, framing requires zero cumulative remainder.

Estimates and calculations are for preliminary planning and layout purposes only. This calculator does not provide structural engineering, load design, or official building code compliance certification. Stair dimensions, maximum riser heights, minimum tread depths, handrail requirements, and minimum vertical headroom clearances are strictly governed by local building codes and municipal ordinances. Always verify measurements with a local building inspector or licensed general contractor before cutting stringers or beginning construction.

Worked Examples

Example 1: 108" Total Rise with 7.75" Target Riser (Check Case)

Inputs: Total Rise = 108 in, Target Max Riser = 7.75 in

Divide total rise by max limit: 108 ÷ 7.75 = 13.935.
Round up to next whole integer: Ceiling(13.935) = 14 risers.
Calculate exact riser height: 108 ÷ 14 = 7.7142857... in (rounds to 7.7143 in).
Verify cumulative sum: 14 × 7.7142857... in = 108.00 in (zero remainder).

Final Answer: 7.7143 in exact riser height (14 identical risers; 108" total rise)

Example 2: 96" Standard 8-Foot Ceiling (Total Rise = 96 in)

Inputs: Total Rise = 96 in, Target Max Riser = 7.75 in

Calculate count: 96 ÷ 7.75 = 12.387 → 13 risers.
Calculate exact height: 96 ÷ 13 = 7.384615... in (7.3846 in).
Check sum: 13 × 7.384615... = 96.00 in.

Final Answer: 7.3846 in exact riser height (13 identical risers; 96" total rise)

Example 3: Feet and Inches Input (9 ft 6 in [114"] Rise at 7.75" Max Riser)

Inputs: Total Rise = 9 ft 6 in (114.0 in), Target Max Riser = 7.75 in

Convert feet and inches: 9 × 12 + 6 = 114.00 in.
Calculate count: 114 ÷ 7.75 = 14.71 → 15 risers.
Calculate height: 114 ÷ 15 = 7.6000 in.
Check sum: 15 × 7.60 = 114.00 in.

Final Answer: 7.6000 in exact riser height (15 identical risers; 114" total rise)

How to Use This Calculator

Enter total vertical floor-to-floor rise in inches (or use the paired feet and inches fields).

Enter your target maximum riser height (default 7.75 inches for residential stairs).

Review the calculated number of risers and exact individual riser height.

Use the exact decimal height on your framing square to lay out stringer step cutouts.

Reference Table

Total Rise	Target Max Riser	Riser Count	Exact Equal Riser Height	Sum Verification
70 in	7.75 in	10 risers	7.0000 in	10 × 7.0000" = 70.00"
84 in	7.75 in	11 risers	7.6364 in	11 × 7.6364" = 84.00"
96 in	7.75 in	13 risers	7.3846 in	13 × 7.3846" = 96.00"
108 in	7.75 in	14 risers	7.7143 in	14 × 7.7143" = 108.00"
114 in	7.75 in	15 risers	7.6000 in	15 × 7.6000" = 114.00"
120 in	7.75 in	16 risers	7.5000 in	16 × 7.5000" = 120.00"

Frequently Asked Questions

What is the maximum allowed riser height for residential stairs?

In the majority of North American residential building codes, the maximum allowable riser height is 7.75 inches (197 mm). In commercial buildings and certain international jurisdictions, the limit is 7.0 inches (178 mm). Always verify local amendments.

Can the bottom or top riser be cut to a different height?

No. While stringers must be trimmed at the bottom to account for tread thickness, the finished step-to-step riser height must remain identical throughout the entire run. Unequal bottom steps are the single most common cause of inspection failure.

How do I handle a repeating decimal riser height during physical framing?

A riser height of 7.7143 inches equals 7 and 23/32 inches (7.7188 in), which differs by only four thousandths of an inch. Using stair gauges clamped to a framing square ensures consistent transfer along the stringer board.

Why does rounding up the riser count prevent out-of-spec steps?

Dividing total rise by a larger count produces a smaller step height. Rounding up to the next whole integer guarantees the individual riser height will be strictly less than or equal to the maximum target limit.

What happens if finished flooring has not yet been installed?

You must account for the thickness of future flooring (subfloor, underlayment, hardwood, tile, carpet) on both the upper and lower floors before establishing total rise. Otherwise, adding flooring later alters the bottom and top riser heights.