📐 Roof Pitch Multiplier Chart
Every pitch from 1/12 to 24/12 with angle, slope %, area multiplier, and hip/valley multiplier.
The formula
Actual Roof Area = Plan Footprint × Pitch Multiplier
Pitch Multiplier = √(1 + (rise/12)²)
Example: 2,000 sqft footprint × 1.1180 (6/12 pitch) = 2,236 sqft of actual roof surface.
| Pitch | Angle (°) | Slope % | Pitch Multiplier | Hip/Valley Mult. |
|---|---|---|---|---|
| 1/12 | 4.764 | 8.33 | 1.0035 | 1.4167 |
| 2/12 | 9.462 | 16.67 | 1.0138 | 1.4240 |
| 3/12 | 14.036 | 25.00 | 1.0308 | 1.4361 |
| 4/12 | 18.435 | 33.33 | 1.0541 | 1.4530 |
| 5/12 | 22.620 | 41.67 | 1.0833 | 1.4743 |
| 6/12 | 26.565 | 50.00 | 1.1180 | 1.5000 |
| 7/12 | 30.256 | 58.33 | 1.1577 | 1.5298 |
| 8/12 | 33.690 | 66.67 | 1.2019 | 1.5635 |
| 9/12 | 36.870 | 75.00 | 1.2500 | 1.6008 |
| 10/12 | 39.806 | 83.33 | 1.3017 | 1.6415 |
| 11/12 | 42.510 | 91.67 | 1.3566 | 1.6853 |
| 12/12 | 45.000 | 100.00 | 1.4142 | 1.7321 |
| 13/12 | 47.291 | 108.33 | 1.4743 | 1.7815 |
| 14/12 | 49.399 | 116.67 | 1.5366 | 1.8333 |
| 15/12 | 51.340 | 125.00 | 1.6008 | 1.8875 |
| 16/12 | 53.130 | 133.33 | 1.6667 | 1.9437 |
| 17/12 | 54.782 | 141.67 | 1.7341 | 2.0017 |
| 18/12 | 56.310 | 150.00 | 1.8028 | 2.0616 |
| 19/12 | 57.724 | 158.33 | 1.8727 | 2.1230 |
| 20/12 | 59.036 | 166.67 | 1.9437 | 2.1858 |
| 21/12 | 60.255 | 175.00 | 2.0156 | 2.2500 |
| 22/12 | 61.390 | 183.33 | 2.0883 | 2.3154 |
| 23/12 | 62.447 | 191.67 | 2.1619 | 2.3819 |
| 24/12 | 63.435 | 200.00 | 2.2361 | 2.4495 |
How contractors use this chart
- Measure home footprint (length × width) from the ground or blueprints.
- Determine pitch using our Roof Pitch Calculator.
- Look up the multiplier in the table above.
- Multiply footprint × multiplier = actual roof area for material orders.
- Use the hip/valley multiplier × horizontal run to size rafters and valley flashing.
FAQ
What is a roof pitch multiplier?
A roof pitch multiplier converts a home's flat (plan-view) footprint into actual sloped roof surface area. For a 6/12 pitch the multiplier is 1.1180, meaning your true roof area is 11.8% larger than the footprint.
How do I use the pitch multiplier?
Actual roof area = Plan footprint × Pitch multiplier. Example: a 2,000 sqft footprint on a 6/12 pitch becomes 2,000 × 1.1180 = 2,236 sqft of shingles.
What's the multiplier for a 6/12 pitch?
1.1180. For 4/12 it's 1.0541. For 9/12 it's 1.2500. For 12/12 it's 1.4142.
What is the hip/valley multiplier?
It's used to calculate the diagonal length of hip and valley rafters. Multiply the horizontal run by √(2 + (rise/12)²).
The roof pitch chart adds the hip/valley multiplier and a degrees-to-pitch table.
Measuring rakes for holiday lights? The Christmas lights calculator does the strand count.
Skip the multiplication: the roof square footage calculator applies the factor for you.
🔗 Related Roofing Calculators
- Roof Area Calculator — Auto-applies pitch multiplier
- Roof Pitch Calculator — Find your pitch from measurements
- Roof Pitch Chart — Visual pitch reference
- Roof Slope Calculator — Convert slope to degrees
· Reviewed by the Smart Roofing Calculator editorial team