# Roof Pitch Calculator

- **URL:** https://codeasystem.com/calculators/construction/roof-pitch-calculator/
- **Category:** construction
- **Description:** Turn a roof’s rise-in-12 pitch into degrees of angle, grade percent and the slope multiplier that scales footprint to roof surface.
- **Primary output:** Angle at 6:12 pitch: 26.57°

## Inputs
- Rise per 12 of run (name: `rise`, type: number, example: 6)
- Building span (optional) (name: `span`, type: number, example: 24)
- Building length (optional) (name: `buildingLength`, type: number, example: 40)

## Outputs
- Angle at 6:12 pitch: 26.57°
- Pitch ratio: 6:12
- Slope (grade): 50%
- Roof area multiplier: 1.12× footprint
- Roof surface for 960 sq ft footprint: 1,073.31 sq ft

## Formula / methodology
```
Angle = atan(rise / 12)
Slope % = rise / 12 × 100
Multiplier = 1 ÷ cos(angle)
```

Pitch written X:12 means the roof climbs X inches for every 12 inches of horizontal run. That ratio defines the angle via arctangent, the grade percentage directly, and the roof-area multiplier as the secant of the angle; the factor that stretches a flat footprint onto the tilted plane.

## Assumptions & limitations
- Simple gable geometry without dormers, hips or overhangs.
- Span treated as building width; overhangs add real-world roof area beyond the footprint.
- Flat roofs (rise 0) legitimately return a 0° angle and 1.00× multiplier.

## How to use
1. **Find the rise**; Measure vertical inches from the top of a 12-inch level held against the rafter; that is the pitch’s first number.
2. **Read the geometry**; The angle, slope percent and multiplier update instantly from the rise alone.
3. **Size the roof surface**; Optionally enter span and building length to convert footprint into sloped roof area for shingle or metal ordering.

## Example
A classic 6:12 pitch rises at 26.57°; a 50% grade whose multiplier of 1.12 turns a 960 sq ft footprint (24×40) into about 1,073 sq ft of roof surface.

Result for these inputs:

```
Angle at 6:12 pitch: 26.57°
```

## About this calculator
### Pitch vs slope vs angle

Carpenters say “six-twelve”, engineers write 50%, and CAD users see 26.57°. All three describe the same ramp: this calculator keeps them side by side because plans, suppliers and code books each pick a different favorite.

### Why the multiplier matters

Shingles are bought by the square (100 sq ft of roof, not footprint). At 12:12 the roof carries 41% more surface than the building below it; forgetting the multiplier is the classic first-roof material shortage.

### Steepness changes everything downstream

Above 6:12 crews move slower and safety gear becomes mandatory; below 3:12 many shingle warranties lapse because water drains too slowly. Pitch is not cosmetic; it selects materials, labor cost and inspection rules.

## FAQs
### What does 6:12 mean exactly?

The roof rises 6 inches for every 12 inches of horizontal run; an angle of about 26.57 degrees, or a 50% grade.

### How do I convert pitch to degrees?

Take the arctangent of rise ÷ 12. This calculator performs that conversion and shows the degree figure directly.

### What is the roof area multiplier?

It is 1 ÷ cos(angle): the amount of extra surface created by tilting a flat plane. Multiply your footprint by it for shingle quantities.

### Does this include overhangs?

No; enter span and length of the structure itself, then add eave width to each side when ordering materials.

## Related calculators
- [Square Footage Calculator](https://codeasystem.com/calculators/construction/square-footage-calculator/)
- [Drywall Calculator](https://codeasystem.com/calculators/construction/drywall-calculator/)
- [Length Converter](https://codeasystem.com/calculators/conversion/length-converter/)

---
Last updated: 2026-08-23 · Version: 1.0.0 · [HTML version](https://codeasystem.com/calculators/construction/roof-pitch-calculator/)