TOOL 16 / FREE · NO SIGNUP
Roofing Area & Bundle Calculator
Calculate roof surface area and whole product bundles. Keep measured surface area separate from horizontal projection and pitch.
Worked example loaded. These are example measurements and product assumptions.
THE METHOD
How to use this estimate
- Use measured total surface directly, or a complete projection at one uniform pitch. Include overhangs in your projection.
- A roofing square is 100 ft². Keep fractional squares until actual bundle purchasing is rounded.
- For different pitches, calculate each section’s actual area and sum those unrounded areas before using direct-surface mode.
surface = projection × √(1 + (rise/run)²); bundles = ceil(surface × allowance factor / bundle coverage)
A worked example
The “Load worked example” button uses the same inputs as this example. Explicit unit suffixes keep their meaning in either unit system.
- Area measurement mode
- Horizontal projection with uniform pitch
- Area in the selected measurement mode
- 600 ft2
- Slope rise (same unit as slope run)
- 9
- Slope horizontal run
- 12
- Ordering allowance
- 10
- Installed coverage per bundle
- 3.096768 m2
- Complete horizontal projection
- 55.742 m² / 600 ft²
- Slope factor
- 1.25
- Measured roof surface area
- 69.677 m² / 750 ft²
- Measured roofing squares (100 ft² each)
- 7.5
- Roofing squares with allowance
- 8.25
- Bundles
- 25
- Purchased installed coverage
- 77.419 m² / 833.333 ft²
- Coverage beyond allowance
- 0.774 m² / 8.333 ft²
Questions, answered
Are there always three bundles in a square?
No. Coverage varies by product. Enter the actual installed coverage from its label.
What does a pitch of 9:12 mean?
Nine units of vertical rise for twelve units of horizontal run. Both numbers use the same unit. It is a dimensionless slope ratio.
Sources and product assumptions
These references explain units or product specifications. Your selected product label takes priority; none of these sources endorses this calculator.
Source check: 4 October 2026. Worked examples use stated, editable assumptions.