What does a pitch like 6:12 mean?

The rise for every 12 of run. A 6:12 roof climbs 6 inches for every 12 inches it goes across, and it is the same roof whether you measure in inches, centimetres or feet, since the pitch is a ratio. Written as a slope it is 6 divided by 12, or 0.5; as a grade it is 50%; as an angle it is 26.57 degrees. Type it as 6:12, 6/12, 6 in 12, or just 6, and the tool reads all four the same way.

How do I convert a roof pitch to degrees?

The angle is the arctangent of the rise over the run. For 6:12 that is arctan(6 / 12) = 26.57 degrees; for 4:12 it is 18.43, for 8:12 it is 33.69, for 12:12 it is exactly 45. The tool does the arctangent for you: switch Given to Pitch, type the pitch, and read the Angle row. Pitch and angle are not proportional, so doubling the pitch does not double the angle; 12:12 is 45 degrees but 24:12 is 63.43, not 90.

How do I get the pitch from an angle?

Switch Given to Angle and type the degrees. The rise per 12 is 12 times the tangent of the angle, so 30 degrees is 12 × tan(30°) = 6.9282, which the tool writes as 6.9282:12. An angle of 90 is a vertical wall with no slope, and the tool says the slope is undefined rather than printing a pitch for it; anything past 90 either way is outside the range of a roof and is refused with the range named.

How do I measure the pitch of an existing roof?

Use a safely accessible measurement or dimensions already provided in a drawing. The rise is the vertical change over a horizontal run in the same units. Enter both as a ratio, such as 4:18; the Pitch row rewrites that as 2.66667:12 and the Distance row keeps your actual rise and run. This browser tool does not measure through a camera or sensor.

Is a roof pitch the same as its slope?

This page uses pitch to mean rise over horizontal run, usually normalized to 12: 6:12 has slope 0.5. Some trades use pitch for rise over the entire roof span instead. On a symmetric 24-foot span with a 6-foot rise, the horizontal run of one side is 12 feet, so this page calls it 6:12 while the rise-to-span ratio is 1:4. Check which convention your dimensions use.

What is the roof slope factor or pitch multiplier?

The Slope factor row gives √(1 + slope²), the ratio of sloping length to horizontal run. A 6:12 pitch has factor 1.11803. For a single plane at that pitch, a horizontal projected area of 1,000 square feet corresponds to about 1,118.03 square feet along the plane. The tool displays the factor; it has no roof-area input and does not account for hips, valleys, openings, overhangs or material waste.

Can I calculate a shed, lean-to or flat roof pitch?

Yes, when you supply its measured rise and horizontal run. A single plane uses the same ratio whatever the building is called, including a shed, lean-to, barn or pergola. A rise of zero gives zero pitch. This geometry does not select a suitable minimum pitch for a material, size trusses or rafters, calculate loads, or check local requirements.

How do I find roof height or length along the slope?

For a measured rise and run, the Distance row gives √(rise² + run²). If you know an angle and an actual length instead, Right Triangle Calculator can solve the missing sides. The Roof pitch Angle input uses a reference run of 12; its distance is not the length of your roof unless that run matches your dimensions.

Roof Pitch Calculator

Type a roof pitch like 6:12 and read its angle in degrees, its slope and its percent grade, or type the angle and get the pitch back as rise per 12. The stage draws the pitch triangle at true scale, and the rows give the slope, the angle, the grade, the length along the slope for the rise and run typed, and the line's equation, each with a copy button. This is the geometry of the pitch only: it does not size rafters or pick materials.

Roof pitch · rise per 12 of run6:1226.57° · slope 0.5 · 50% grade

Mode

Given

Pitch (rise:run)

A pitch is the rise per 12 of run: 6:12 climbs 6 for every 12 across. Type it as 6:12, 6/12 or just 6, or give the angle instead.

Pitchrise per 12 of run
6:12
Angledegrees above horizontal, arctan of the slope
26.5650511771°
Sloperise / run
0.5
Percent gradeslope × 100
50%
Distancealong the slope, for the rise and run given
13.416407865
Slope factorsloping length / horizontal run, √(1 + slope²)
1.11803398875
Equationy = mx + b, to four places
y = 0.5x + 0

The same line in several forms. Slope is rise divided by run. The angle is the arctangent of the slope, in degrees above horizontal, so 45 degrees is a slope of 1. Percent grade is the slope times 100, the number a road sign uses. Distance is the straight length between the two points, from Pythagoras. The equation is the slope-intercept form y = mx + b, with b where the line crosses the y axis. And a roof pitch is the same slope written as the rise per 12 of run, so 6:12 is a slope of 0.5, a 50% grade and an angle of 26.57 degrees. A vertical line has no slope at all: the run is 0, and the tool says so instead of printing infinity.

Roof pitch to degrees and grade chart

Rise per 12 units of horizontal run. Angles and slope factors are rounded; values describe geometry only.

Pitch	Degrees	Grade	Slope factor
0:12	0.00°	0.00%	1.00000
1:12	4.76°	8.33%	1.00347
2:12	9.46°	16.67%	1.01379
3:12	14.04°	25.00%	1.03078
4:12	18.43°	33.33%	1.05409
5:12	22.62°	41.67%	1.08333
6:12	26.57°	50.00%	1.11803
7:12	30.26°	58.33%	1.15770
8:12	33.69°	66.67%	1.20185
9:12	36.87°	75.00%	1.25000
10:12	39.81°	83.33%	1.30171
11:12	42.51°	91.67%	1.35657
12:12	45.00°	100.00%	1.41421

Common questions

What does a pitch like 6:12 mean?: The rise for every 12 of run. A 6:12 roof climbs 6 inches for every 12 inches it goes across, and it is the same roof whether you measure in inches, centimetres or feet, since the pitch is a ratio. Written as a slope it is 6 divided by 12, or 0.5; as a grade it is 50%; as an angle it is 26.57 degrees. Type it as 6:12, 6/12, 6 in 12, or just 6, and the tool reads all four the same way.
How do I convert a roof pitch to degrees?: The angle is the arctangent of the rise over the run. For 6:12 that is arctan(6 / 12) = 26.57 degrees; for 4:12 it is 18.43, for 8:12 it is 33.69, for 12:12 it is exactly 45. The tool does the arctangent for you: switch Given to Pitch, type the pitch, and read the Angle row. Pitch and angle are not proportional, so doubling the pitch does not double the angle; 12:12 is 45 degrees but 24:12 is 63.43, not 90.
How do I get the pitch from an angle?: Switch Given to Angle and type the degrees. The rise per 12 is 12 times the tangent of the angle, so 30 degrees is 12 × tan(30°) = 6.9282, which the tool writes as 6.9282:12. An angle of 90 is a vertical wall with no slope, and the tool says the slope is undefined rather than printing a pitch for it; anything past 90 either way is outside the range of a roof and is refused with the range named.
How do I measure the pitch of an existing roof?: Use a safely accessible measurement or dimensions already provided in a drawing. The rise is the vertical change over a horizontal run in the same units. Enter both as a ratio, such as 4:18; the Pitch row rewrites that as 2.66667:12 and the Distance row keeps your actual rise and run. This browser tool does not measure through a camera or sensor.
Is a roof pitch the same as its slope?: This page uses pitch to mean rise over horizontal run, usually normalized to 12: 6:12 has slope 0.5. Some trades use pitch for rise over the entire roof span instead. On a symmetric 24-foot span with a 6-foot rise, the horizontal run of one side is 12 feet, so this page calls it 6:12 while the rise-to-span ratio is 1:4. Check which convention your dimensions use.
What is the roof slope factor or pitch multiplier?: The Slope factor row gives √(1 + slope²), the ratio of sloping length to horizontal run. A 6:12 pitch has factor 1.11803. For a single plane at that pitch, a horizontal projected area of 1,000 square feet corresponds to about 1,118.03 square feet along the plane. The tool displays the factor; it has no roof-area input and does not account for hips, valleys, openings, overhangs or material waste.
Can I calculate a shed, lean-to or flat roof pitch?: Yes, when you supply its measured rise and horizontal run. A single plane uses the same ratio whatever the building is called, including a shed, lean-to, barn or pergola. A rise of zero gives zero pitch. This geometry does not select a suitable minimum pitch for a material, size trusses or rafters, calculate loads, or check local requirements.
How do I find roof height or length along the slope?: For a measured rise and run, the Distance row gives √(rise² + run²). If you know an angle and an actual length instead, Right Triangle Calculator can solve the missing sides. The Roof pitch Angle input uses a reference run of 12; its distance is not the length of your roof unless that run matches your dimensions.

Double-precision geometry from your numbers. Equations round coefficients to four decimal places; other readings show up to twelve significant digits. This calculates a line's geometry, not structural capacity or construction compliance.