What is a 4:12 roof pitch in degrees?

18.43°, a 33.3% slope. It's the shallowest pitch normally allowed for standard asphalt shingles.

What roof pitch is 45 degrees?

A 12:12 pitch — the rise equals the run. It's about the steepest pitch used on ordinary houses; anything past it usually means a specialty design or a mansard.

What is the most common residential roof pitch?

Between 4:12 and 9:12, roughly 18° to 37°. That range sheds water and snow well while staying walkable enough to roof safely.

How do I convert an x:12 pitch to degrees?

Take the arctangent of x ÷ 12 and multiply by 57.2958. A 6:12 pitch is atan(6/12) × 57.2958 = 26.57°.

Can I use this with metric measurements?

Yes. Pitch is a ratio, so the units cancel. Enter rise and run both in millimetres, or both in centimetres, and the angle comes out the same.

What pitch do I need for solar panels?

Panel output favours a tilt near your latitude, often 25° to 40°. This converter gives the roof's existing angle so you can decide whether panels lie flush or need a tilt frame.

Roof Pitch to Degrees Calculator

Roofers talk in pitch — “it’s a 6:12” — but plenty of things need the angle in degrees instead: a miter saw setting for rake trim, a building-code slope minimum, a solar-panel tilt calculation, a truss order. Pitch and degrees describe the same slope; this converter moves between them, and throws in the slope percentage used on drainage plans.

The roof pitch to degrees formula

is the angle in degrees. The slope percentage and the standard x:12 ratio come from the same rise/run fraction:

Worked example

The calculator’s defaults are a rise of 4 and a run of 12.

So a 4:12 pitch is 18.43° and a 33.3% slope.

Roof Pitch to Degrees Calculator worked example diagram — A visual read of the worked example above — the same numbers the calculator returns for its default inputs.

Common roof pitch angles: pitch, degrees and slope

Pitch (x:12)	Degrees	Slope %	Typical use
1:12	4.76°	8.3%	low-slope membrane, minimum for standing seam
2:12	9.46°	16.7%	rolled roofing, minimum for many metal panels
3:12	14.04°	25.0%	shingle minimum with special underlayment
4:12	18.43°	33.3%	standard asphalt-shingle minimum
6:12	26.57°	50.0%	common residential, still walkable
8:12	33.69°	66.7%	steep residential, roof jacks needed
12:12	45.00°	100.0%	very steep, cathedral and Victorian styles
18:12	56.31°	150.0%	steeple and turret territory

Lower angles drain slowly and rely on the underlayment or membrane to stay watertight; anything under 2:12 usually can’t use shingles at all. Steeper angles shed water and snow fast but need more material (the sloped surface is larger than the footprint) and fall-protection to work on.

Common mistakes

Confusing run with span. Run is the horizontal distance from the wall to the ridge — half the span on a symmetric gable.
Measuring the rafter length as the run. The run is horizontal; the rafter is the hypotenuse.
Mixing units between rise and run. Both must match; the ratio is what matters.

Measuring pitch on site

Hold a level horizontally against the underside of a rafter or on the roof deck. Measure 12 inches along the level from the point touching the roof, then measure straight down from that 12-inch mark to the roof surface — that vertical distance is the rise for a run of 12, i.e. the x in x:12.

Tips for Accurate Measurement

Use a 12-inch level and a tape measure against a rafter or the roof deck to get rise and run directly. If you’re measuring from blueprints, the rise and span (total width) are often noted; remember that run is half the span for a symmetric gable roof. Always measure in the same units for both values since the ratio is unitless.

Going from degrees back to pitch

Take the tangent of the angle and multiply by 12. A roof at 30°:

That’s just under a 7:12 pitch. Plans from metric countries often give the angle, so this is the conversion to use when ordering trusses or reading a US spec.

Rafter length and roof area

Pitch also tells you how much longer the sloped surface is than its flat footprint. The pitch multiplier is the hypotenuse of a triangle with a run of 1:

For a 6:12 roof, . A 12-foot run then needs a rafter about feet long before the overhang. The same multiplier turns a footprint into roof area: a 40 × 30 ft footprint at 6:12 has about square feet of roof, or roughly 13.4 roofing squares of 100 square feet each.

Pitch and roofing materials

Below 2:12 (about 9.5°): treated as a low-slope roof, needing a membrane such as EPDM or TPO rather than shingles.
2:12 to 4:12: shingles are possible with extra underlayment; check the manufacturer’s minimum.
4:12 and steeper: standard asphalt shingle territory.
Above about 9:12: walkable only with roof jacks or harnesses, which adds labour cost.

About the formula: The angle equals the arctangent of rise divided by run, converted from radians to degrees.