A stair rise and run chart turns a total rise into the number of risers, the equal riser height, the treads and the total run. A 42 in rise needs 6 risers of 7.000 in and 5 treads, which at a 10 in tread is 4′ 2″ of run. The chart covers total rises from 12 to 120 in with a 7 3/4 in maximum riser and a 10 in tread, adds an angle chart for riser and tread pairs, and prints as a one-page PDF.
Stair rise and run chart by total rise
Find your finished total rise in the first column to read the number of risers, the equal riser height, the number of treads, the total run and the stair angle. Quick answers: 24 in needs 4 risers of 6.000 in and 3 treads; 36 in needs 5 risers of 7.200 in and 4 treads; 48 in needs 7 risers of 6.857 in and 6 treads.
Counts use a maximum riser of 7 3/4 in and a tread run of 10 in, the 2021 IRC residential reference described under Sources. Treads are one fewer than risers when the upper floor or deck is the last walking surface.
| Total rise | Risers | Riser height | Treads | Total run | Angle | Stringer line |
|---|---|---|---|---|---|---|
| 12 in (1′ 0″) | 2 | 6.000 in (6″) | 1 | 0′ 10″ | 31.0° | 1′ 3 5/8″ |
| 18 in (1′ 6″) | 3 | 6.000 in (6″) | 2 | 1′ 8″ | 31.0° | 2′ 2 15/16″ |
| 24 in (2′ 0″) | 4 | 6.000 in (6″) | 3 | 2′ 6″ | 31.0° | 3′ 2 7/16″ |
| 30 in (2′ 6″) | 4 | 7.500 in (7 1/2″) | 3 | 2′ 6″ | 36.9° | 3′ 6 7/16″ |
| 36 in (3′ 0″) | 5 | 7.200 in (7 3/16″) | 4 | 3′ 4″ | 35.8° | 4′ 5 13/16″ |
| 42 in (3′ 6″) | 6 | 7.000 in (7″) | 5 | 4′ 2″ | 35.0° | 5′ 5 5/16″ |
| 48 in (4′ 0″) | 7 | 6.857 in (6 7/8″) | 6 | 5′ 0″ | 34.4° | 6′ 4 13/16″ |
| 54 in (4′ 6″) | 7 | 7.714 in (7 11/16″) | 6 | 5′ 0″ | 37.6° | 6′ 8 3/4″ |
| 60 in (5′ 0″) | 8 | 7.500 in (7 1/2″) | 7 | 5′ 10″ | 36.9° | 7′ 8 3/16″ |
| 66 in (5′ 6″) | 9 | 7.333 in (7 5/16″) | 8 | 6′ 8″ | 36.3° | 8′ 7 11/16″ |
| 72 in (6′ 0″) | 10 | 7.200 in (7 3/16″) | 9 | 7′ 6″ | 35.8° | 9′ 7 1/4″ |
| 78 in (6′ 6″) | 11 | 7.091 in (7 1/16″) | 10 | 8′ 4″ | 35.3° | 10′ 6 13/16″ |
| 84 in (7′ 0″) | 11 | 7.636 in (7 5/8″) | 10 | 8′ 4″ | 37.4° | 10′ 10 5/8″ |
| 90 in (7′ 6″) | 12 | 7.500 in (7 1/2″) | 11 | 9′ 2″ | 36.9° | 11′ 10 1/8″ |
| 96 in (8′ 0″) | 13 | 7.385 in (7 3/8″) | 12 | 10′ 0″ | 36.4° | 12′ 9 11/16″ |
| 102 in (8′ 6″) | 14 | 7.286 in (7 5/16″) | 13 | 10′ 10″ | 36.1° | 13′ 9 1/4″ |
| 108 in (9′ 0″) | 14 | 7.714 in (7 11/16″) | 13 | 10′ 10″ | 37.6° | 14′ 1″ |
| 114 in (9′ 6″) | 15 | 7.600 in (7 5/8″) | 14 | 11′ 8″ | 37.2° | 15′ 0 9/16″ |
| 120 in (10′ 0″) | 16 | 7.500 in (7 1/2″) | 15 | 12′ 6″ | 36.9° | 16′ 0 1/16″ |
The stringer line is the straight distance along the tread nosings, √(total rise² + total run²). It is a geometric length, not a board length: the board has to be longer to cover the cuts at both ends. To start from your own total rise, maximum riser or tread, use the stair calculator, or download this chart as a one-page PDF to print for the shop or the site.
Stair angle chart: riser and tread
The angle of a stair is atan(riser ÷ tread). It depends only on the riser height and the tread run, not on the total rise. A 7 in riser with a 10 in tread is 35.0°, and with an 11 in tread it is 32.5°.
| Riser height | 9″ tread | 10″ tread | 10 1/2″ tread | 11″ tread | 12″ tread |
|---|---|---|---|---|---|
| 6″ riser | 33.7° | 31.0° | 29.7° | 28.6° | 26.6° |
| 6 1/2″ riser | 35.8° | 33.0° | 31.8° | 30.6° | 28.4° |
| 7″ riser | 37.9° | 35.0° | 33.7° | 32.5° | 30.3° |
| 7 1/4″ riser | 38.9° | 35.9° | 34.6° | 33.4° | 31.1° |
| 7 1/2″ riser | 39.8° | 36.9° | 35.5° | 34.3° | 32.0° |
| 7 3/4″ riser | 40.7° | 37.8° | 36.4° | 35.2° | 32.9° |
Tread run is measured between successive nosings. These are angles only; they do not say whether a combination meets the code in your area.
How to read the stair chart
- Measure the total rise from the finished lower floor to the finished upper floor, including any flooring or tread thickness still to be added.
- Find the row for that rise. If it falls between two rows, do not interpolate: the riser count changes in whole steps, so enter the exact rise in the stair calculator.
- Read the riser count and height. Divide the total rise by the riser count to get the exact equal riser height. Use that exact value when you lay out the stringer.
- Multiply the treads by the tread run to get the total run, then compare it with the floor length you have. The stairwell opening calculator turns the layout into a floor opening length.
Worked example: a 42 in deck stair
A deck surface is 42 in above the landing pad. Use the 7 3/4 in maximum riser and a 10 in tread, and let the deck be the top walking surface.
| Step | Calculation | Result |
|---|---|---|
| Risers | 42 ÷ 7.75 = 5.42, rounded up | 6 |
| Riser height | 42 ÷ 6 | 7.000 in |
| Treads | 6 − 1 | 5 |
| Total run | 5 × 10 in | 50 in (4′ 2″) |
| Angle | atan(7 ÷ 10) | 35.0° |
| Stringer line | √(42² + 50²) | 65.30 in (5′ 5 5/16″) |
The exact riser height here is a whole number, which is convenient. Most rises are not: 96 in gives 13 risers of 7.385 in, and the layout should use that exact value, not a rounded 7 3/8 in on every step.
Mistakes that make the chart wrong for your stair
- Measuring to the unfinished floor. Rise is finished floor to finished floor. If flooring or tread thickness is added later, the first or last riser will not match the others.
- Counting as many treads as risers. When the upper floor is the last walking surface, a flight has one fewer tread than risers. A landing or a separate top tread changes the count, so sketch the whole flight first.
- Rounding the riser height. Use the exact value, such as 7.385 in, and mark from the top with a stair gauge or dividers so rounding does not add up across the flight.
- Ignoring the available run. A 10 in tread gives the run in the table. If the floor is shorter, a different tread or a different layout is needed, and the stairwell opening has to be long enough for the flight.
- Reading the chart as a code check. It uses one residential reference and says nothing about local amendments, landings, handrails or commercial stairs.
Sources
Residential stair limits are in the International Residential Code, Section R311.7. The 2021 edition sets a maximum riser height of 7¾ in in R311.7.5.1 and a minimum tread depth of 10 in in R311.7.5.2, published by the International Code Council. Your jurisdiction adopts a specific edition and may amend it, and commercial stairs (IBC) and other countries use different values. Tables and examples here are generated from this site’s calculator functions.
Frequently asked questions
How many steps do I need for a 24 inch rise?
24 in needs 4 risers of 6.000 in (24 ÷ 7.75 = 3.10, rounded up). With the upper floor or deck as the last walking surface that is 3 treads, and a 10 in tread gives a total run of 2′ 6″.
How do I find the number of stairs from the total rise?
Divide the finished total rise by your maximum riser height and round up to get the number of risers. Divide the total rise by that count for the equal riser height. The chart does this for total rises from 12 to 120 in, using a 7 3/4 in maximum riser.
What is the angle of a 7 inch riser and 10 inch tread?
atan(7 ÷ 10) = 35.0°. With an 11 in tread the angle is 32.5°. The stair angle chart lists the angle for other riser and tread pairs.
What is the 7-11 rule for stairs?
It usually refers to a riser of about 7 in with a tread of about 11 in. It is a planning pair, not a universal requirement. Code limits are a maximum riser and a minimum tread that your jurisdiction sets, so check the edition and amendments where you build.
Why are there fewer treads than risers?
The upper floor or deck is the last walking surface, so a flight with 14 risers has 13 treads. A landing or a separate top tread changes the count.
Does the chart include nosing, flooring or code approval?
No. The values are geometric. Measure total rise to the finished floors, add any flooring or tread thickness first, and check the layout against the code your inspector enforces.