Hip Roof Area Calculator

Measuring a roof is one of the most dangerous and difficult tasks in construction. Climbing ladders, walking on steep pitches, and dealing with complex angles makes manual measurement risky. The Roof Area Calculator allows you to estimate the total roofing surface area safely from the ground. By measuring the “footprint” (length and width of the house) and knowing the “pitch” (slope), this tool uses trigonometry to calculate the exact square footage needed for shingles, underlayment, and plywood.

Understanding Roof Pitch

The area of a roof is always larger than the area of the floor below it because of the slope. The steeper the slope, the greater the surface area.

Rise over Run

In the US, pitch is expressed as “Rise over 12”. A 4/12 pitch rises 4 inches for every 12 inches of horizontal run. A 12/12 pitch is a 45-degree angle.

The Pitch Multiplier

We use a “Pitch Multiplier” (or Roof Factor) to convert flat area to sloped area.

For example, a 12/12 pitch has a multiplier of 1.414. This means a 1000 sq ft house needs 1414 sq ft of shingles.

From Area to Materials

Roofers don’t order by the square foot; they order by the “Square” and the “Bundle”.

What is a “Square”?

In roofing lingo, One Square = 100 Square Feet. If your roof is 2,400 sq ft, you need 24 Squares of material.

Shingle Bundles

Standard 3-tab or architectural shingles typically cover 33.3 sq ft per bundle. Therefore, 3 Bundles = 1 Square. Our calculator rounds up to the nearest bundle to ensure you have full coverage.

Accounting for Waste

You never order the exact area. You need extra material for cutting, starter rows, and ridges. Recommended waste factors:

• Gable Roof (Simple): 5-7% waste.
• Hip Roof (Medium): 10-12% waste.
• Complex (Valleys/Dormers): 15-20% waste.

Our calculator allows you to select a “Complexity” level to automatically add the correct safety margin.

Frequently Asked Questions (FAQ)

1. Does this include the overhang?

You must include the overhang (eaves and rakes) in your Length/Width inputs. A 1-foot overhang on a 50-foot house adds 50 sq ft per side—it adds up quickly!

2. How do I find the pitch without climbing?

Go into the attic with a level and tape measure. Measure 12 inches horizontally on a rafter, then measure the vertical rise. Or simply use a “Pitch Gauge” app on your smartphone from the street.

3. What about metal roofing?

The area math is the same. However, metal panels are cut to length. You should use the “Rafter Length” output to order panels of the correct size.

Final Words

Roofing is expensive, and returns are a hassle. The Roof Area Calculator bridges the gap between the blueprint and the lumberyard, ensuring you buy exactly what you need to keep the weather out.