Free Conversion Tool

Roof Pitch Change Calculator

This roof pitch change calculator converts between all roof slope measurement formats: x:12 ratio, degrees, percentage grade (%), and rise-over-run fraction. Roofing professionals in the United States use x:12 notation, European contractors use degrees, and civil engineers use percentage grade. The calculator performs instant bi-directional conversion between all formats and supports both imperial (feet, inches) and metric (meters, centimeters) unit systems.

swap_horiz Pitch Format Visualizer

RUN (12) 6 26.6°
Ratio6:12
Degrees26.57°
Grade50.0%
TypeConventional
swap_horiz Pitch Conversion Input
sync_alt All Pitch Formats
Pitch (x:12)—
Degrees (°)—
Percentage (%)—
Rise per Foot—
Pitch Multiplier—
Roof Type—

How to Convert Roof Pitch Formats

All roof pitch formats express the same slope angle differently. Converting between them requires basic trigonometry: the ratio, the arctangent, and the percentage are all derived from the same rise and run measurements.

tune Drag the Slider to Change Pitch
Run Rise Slope 26.57°
0.5:12 24:12
Angle 26.57°
Grade 50.0%
Multiplier 1.118
Type Conventional
1
swap_horiz

Identify Input Format

2
functions

Apply Conversion Formula

3
check_circle

Verify the Result

Pitch Conversion Formulas

Conversion formulas between all standard roof pitch formats:

straighten Ratio to Degrees
Degrees = arctan(Rise ÷ 12) × (180 ÷ π)
arctan(6 ÷ 12) × 57.296 = 26.57°
rotate_right Ratio to Percentage
Grade % = (Rise ÷ 12) × 100
(6 ÷ 12) × 100 = 50% grade
percent Degrees to Ratio
Rise = tan(Degrees) × 12
tan(26.57°) × 12 = 6:12 pitch
science Live Formula Calculator
ft
ft
Pitch 6 : 12
Angle 26.57°
Grade 50.0%
Rafter 13.42 ft
Multiplier 1.118

Pitch Conversion Reference Chart

Click any row to see the pitch angle visualized. The chart covers all standard pitches from flat (1:12) to steep (12:12) with walkability ratings, material compatibility, and snow shedding performance.

Pitch Angle Grade Multiplier Type Walkability Snow Shedding
1:12 4.76° 8.3% 1.003 Flat/Low Easy Poor
2:12 9.46° 16.7% 1.014 Low Slope Easy Poor
3:12 14.04° 25.0% 1.031 Low Slope Easy Fair
4:12 18.43° 33.3% 1.054 Conventional Easy Fair
5:12 22.62° 41.7% 1.083 Conventional Easy Good
6:12 26.57° 50.0% 1.118 Conventional Moderate Good
7:12 30.26° 58.3% 1.158 Conventional Caution Very Good
8:12 33.69° 66.7% 1.202 Conventional Caution Very Good
9:12 36.87° 75.0% 1.250 Steep Unsafe Excellent
10:12 39.81° 83.3% 1.302 Steep Unsafe Excellent
11:12 42.51° 91.7% 1.357 Steep Unsafe Excellent
12:12 45.00° 100.0% 1.414 Steep Unsafe Excellent
6:12 — 26.57°
Compatible: All Types

FAQs

Answers to the 14 most common questions about roof pitch, slope angle, walkability, snow load, and roofing materials.

How do I convert roof pitch to degrees?

Use the formula: Degrees = arctan(Rise ÷ 12) × (180 ÷ π). For 6:12 pitch: arctan(6/12) = arctan(0.5) = 26.57°. For 4:12 pitch: arctan(4/12) = 18.43°. For 12:12 pitch: arctan(12/12) = 45.00°.

How do I convert degrees to roof pitch?

Use the formula: Pitch = tan(degrees) × 12. For 30°: tan(30°) × 12 = 6.93:12. For 45°: tan(45°) × 12 = 12:12. For 15°: tan(15°) × 12 = 3.22:12.

What is the difference between pitch and slope?

Pitch is traditionally the ratio of rise to full span (ridge to ridge), while slope is rise per 12 inches of run (half span). In modern usage, the terms are used interchangeably to mean rise:12 run. A '6 pitch' roof has 6 inches of rise per 12 inches of run.

What is percentage grade on a roof?

Percentage grade = (rise ÷ run) × 100. A 6:12 pitch = 50% grade. A 4:12 pitch = 33.3% grade. A 12:12 pitch = 100% grade. Grade percentage is commonly used in civil engineering and European construction standards.

How steep is a 4/12 pitch in degrees?

A 4:12 pitch equals 18.43 degrees. This is a moderate slope classified as 'conventional' pitch. It is walkable for roofing work and compatible with most roofing materials including asphalt shingles, metal panels, and tile.

What is the steepest possible roof pitch?

There is no theoretical maximum pitch, but practical pitches rarely exceed 24:12 (63.43°). A-frame cabins use 24:12. Church steeples may exceed 30:12. Above 18:12 (56.3°), walls and roofs effectively merge, requiring wall-type cladding systems.