What angle is a 6/12 roof pitch?

A 6/12 (6:12) roof pitch equals an angle of 26.6° and a 50% slope grade, with a rafter factor of 1.118 (13.42 inches of rafter per foot of run). It is one of the most common pitches on US homes.

How do I convert pitch to degrees?

Convert pitch to degrees with: angle = arctan(rise / 12). For example, arctan(6/12) = arctan(0.5) = 26.57°, so a 6:12 pitch is a 26.6° angle. The conversion chart above lists the angle for every pitch from 1/4:12 to 24:12.

How does the rafter factor work?

Multiply your horizontal run by the rafter factor to get the true hypotenuse rafter length: rafter length = run × √(1 + (rise/run)²). A 6:12 pitch has a factor of 1.118, so a 12-foot run needs a 13.42-foot rafter before adding overhang.

Roof Pitch Chart

Conversion table from 1/4:12 flat slope to 24:12 steep pitch with angles, percentages, and rafter factors.

Last updated November 7, 2026Rafter factors per standard carpentry references (IBC Ch. 15 / IRC R905 material limits)

Roof Pitch = Rise / Run

Pitch is the vertical rise in inches for every 12 inches of horizontal run. A 6/12 roof rises 6 inches per foot of run — the steeper the ratio, the taller the roof below.

Visual pitch comparison from 1/12 (2.4°) to 18/12 (56.3°). Full angle, slope, and rafter data for every pitch is in the conversion table below.

Showing 18 of 18 standard pitches

RoofCal — Roof Pitch Conversion Chart

Standard Carpentry & Framing Rafter Factors (IBC / IRC Compliant)

Generated via RoofCal

2026-11-07

Pitch (X:12)	Angle (°)	Slope (%)	Rafter Factor	Rafter / Ft Run	Classification	Permitted Materials	Action
1/4 : 12	1.2°	2.1%	1.000	12.00"	Flat (Low Slope)	EPDM, TPO, BUR	Calculate
1/2 : 12	2.4°	4.2%	1.001	12.01"	Flat (Low Slope)	EPDM, TPO, PVC	Calculate
1 : 12	4.8°	8.3%	1.003	12.04"	Low Slope	Standing seam / Membrane	Calculate
2 : 12	9.5°	16.7%	1.014	12.17"	Low Slope Limit	Asphalt shingle (double underlayment)	Calculate
3 : 12	14°	25%	1.031	12.37"	Conventional	Asphalt shingle / Metal	Calculate
4 : 12	18.4°	33.3%	1.054	12.65"	Standard Conventional	Standard Shingle / Tile	Calculate
5 : 12	22.6°	41.7%	1.083	13.00"	Standard	All standard roofing	Calculate
6 : 12	26.6°	50%	1.118	13.42"	Standard Walkable	All standard roofing	Calculate
7 : 12	30.3°	58.3%	1.158	13.89"	Standard Walkable Limit	All standard roofing	Calculate
8 : 12	33.7°	66.7%	1.202	14.42"	Steep (Non-walkable)	Shingle, Tile, Slate	Calculate
9 : 12	36.9°	75%	1.250	15.00"	Steep	Shingle, Tile, Slate	Calculate
10 : 12	39.8°	83.3%	1.302	15.62"	Steep	All steep materials	Calculate
11 : 12	42.5°	91.7%	1.357	16.28"	Steep	All steep materials	Calculate
12 : 12	45°	100%	1.414	16.97"	45° Pitch	All steep materials	Calculate
14 : 12	49.4°	116.7%	1.537	18.44"	Very Steep	Slate, Heavy Architectural	Calculate
16 : 12	53.1°	133.3%	1.667	20.00"	Very Steep / Mansard	Slate, Metal, Shingle	Calculate
18 : 12	56.3°	150%	1.803	21.63"	Mansard / A-Frame	Metal, Slate, Shingle	Calculate
24 : 12	63.4°	200%	2.236	26.83"	Gothic / A-Frame	Specialty vertical siding/slate	Calculate

How Rafter Factor Works: Multiply your building run (in feet or inches) by the rafter factor in the table above to find the exact hypotenuse rafter length before adding overhang.

Formula: Rafter Length = Run × √(1 + (Rise/Run)²)

A note on walking on roofs: pitch alone does not determine whether a roof can be walked safely. Surface material, moisture, weather, roof structure and condition, and proper fall protection all matter. Treat the “walkable” classifications above as rough industry conventions only — use appropriate personal fall-arrest systems and follow OSHA fall-protection requirements, or leave roof access to professionals.

Related Roofing Tools

Frequently Asked Questions

A 4/12 (4:12) roof pitch equals an angle of 18.4° and a 33.3% slope grade. Its rafter length factor is 1.054, so each foot of horizontal run produces 12.65 inches of rafter length. It is the minimum pitch for standard asphalt shingle underlayment.