Roof pitch calculator
Enter an address and get that roof’s pitch in seconds — no ladder, no level, no rise and run. Or measure it yourself further down the page.
Free · No signup · Reads a 3D satellite model of the roof, not a database of guesses
Already have measurements?
Enter rise and run — or the roof angle — for the pitch ratio, the angle in degrees, the slope percentage and the pitch multiplier.
Measurements
Measure rise over a 12" run with a level, or enter the angle.
Vertical drop measured from the 12-inch mark on your level down to the roof.
Horizontal distance — keep the default 12 for a standard pitch reading.
6/12
Roof pitch
26.6°
Roof angle
The numbers
- Pitch multiplier (footprint → roof area)
- 1.118
- Slope
- 50.0%
- Category
- Conventional
4/12–6/12 — standard walkable pitch; no steep charges apply.
Working an insurance claim? Pitches of 7/12 and up qualify for steep-slope charges — a separate line item adjusters routinely miss. Photograph a pitch gauge on every plane and check the scope against the Xactimate supplement list.
How to calculate roof pitch
Roof pitch is rise ÷ run × 12 — the inches a roof climbs over 12 inches of horizontal distance, written as X/12. There are four ways to get those two numbers, from fastest to most precise.
- 1
Look it up by address
The fastest method, and the only one that needs no ladder: type the address into the calculator above. It reads the pitch of every roof plane off a 3D satellite model of that exact house and returns the predominant pitch in X/12 form, usually in a couple of seconds.
- 2
Measure rise over a 12-inch run with a level
The classic method. Hold a 24-inch level horizontally against the roof surface (or against a rafter in the attic, which is safer). Mark 12 inches out along the level from the end touching the roof. Measure straight down from that 12-inch mark to the roof surface. That vertical distance in inches is your rise — 5 inches means a 5/12 pitch.
- 3
Read the angle and convert it
Lay a smartphone level or an inclinometer flat on the roof surface, or on the top edge of a rafter, and read the angle in degrees. Enter it in the Angle tab above. A 26.6° roof is 6/12; a 33.7° roof is 8/12. Pitch = tan(angle) × 12.
- 4
Measure a gable end from the ground
No roof access at all: photograph the gable end square-on from the ground. Measure the total width of the gable (the run is half of that width) and the vertical height from the top of the wall to the peak (the rise). Divide rise by run, then multiply by 12. A gable 32 feet wide with a 5.33-foot rise is 5.33 ÷ 16 × 12 = 4/12.
Worked example. A level held against the roof reads 7 inches of drop at the 12-inch mark. The pitch is 7/12. The angle is arctan(7 ÷ 12) = 30.3°. The slope is 7 ÷ 12 = 58.3%. The pitch multiplier is √(7² + 12²) ÷ 12 = 1.158, so a 1,600 sq ft footprint is about 1,853 sq ft of roof.
Roof pitch chart: angle, slope & multiplier for every pitch
Degrees, slope percentage and pitch multipliers for standard pitches. Multiply the building footprint by the multiplier to get true roof surface area.
| Pitch | Angle | Slope | Multiplier |
|---|---|---|---|
| 1/12 | 4.8° | 8.3% | 1.003 |
| 2/12 | 9.5° | 16.7% | 1.014 |
| 3/12 | 14.0° | 25.0% | 1.031 |
| 4/12 | 18.4° | 33.3% | 1.054 |
| 5/12 | 22.6° | 41.7% | 1.083 |
| 6/12 | 26.6° | 50.0% | 1.118 |
| 7/12 — steep charges start | 30.3° | 58.3% | 1.158 |
| 8/12 | 33.7° | 66.7% | 1.202 |
| 9/12 | 36.9° | 75.0% | 1.250 |
| 10/12 | 39.8° | 83.3% | 1.302 |
| 11/12 | 42.5° | 91.7% | 1.357 |
| 12/12 | 45.0° | 100.0% | 1.414 |
| 13/12 | 47.3° | 108.3% | 1.474 |
| 14/12 | 49.4° | 116.7% | 1.537 |
| 15/12 | 51.3° | 125.0% | 1.601 |
| 16/12 | 53.1° | 133.3% | 1.667 |
| 17/12 | 54.8° | 141.7% | 1.734 |
| 18/12 | 56.3° | 150.0% | 1.803 |
How to calculate roof square footage from pitch
A roof is always bigger than the house underneath it, and the pitch is what says by how much. Three steps:
- 1.Measure the building footprint in square feet — length × width of the covered area, including overhangs.
- 2.Multiply by the pitch multiplier from the chart above (or from the calculator).
- 3.Divide by 100 for roofing squares, then add 10–15% waste before ordering.
The address bar at the top skips all of it — it returns the sloped roof area straight from the 3D model, already accounting for pitch. The roof square footage calculator leads with that number and turns it into squares and bundles.
Roof pitch vs roof slope
On a job site the two words mean the same thing, and a roof slope calculator does the same arithmetic as a roof pitch calculator. Strictly, slope is rise over horizontal run (6/12) while pitch is rise over the whole span (6/24 on the same roof) — but nobody writes it that way in practice. Slope also gets quoted as a percentage: a 6/12 roof is a 50% slope.
Keep going
Roof square footage calculator — area, squares and shingle bundles from the same address.
Roof replacement cost calculator — what a new roof runs on that house.
What is a roofing square? — the unit every estimate is written in.
Hail damage lookup — check whether that roof has been hit.
Roof pitch questions, answered
Roof pitch is rise divided by run, expressed per 12 inches of run. Measure how many inches the roof rises over 12 inches of horizontal distance — that number is the pitch. A roof rising 6 inches over a 12-inch run is a 6/12 pitch. If you know the angle instead, pitch = tan(angle in degrees) × 12. And if you would rather not measure anything, enter the address at the top of this page and the pitch is read off a 3D satellite model of the house.