One roofing square equals 100 square feet of roof surface. Roof area = footprint area x pitch multiplier, then squares = roof area / 100. A 6/12 pitch has a multiplier of about 1.118, so a 2,000 sq ft footprint is roughly 2,236 sq ft of roof, or 22.4 squares before waste. Architectural shingles are typically sold three bundles per square.
Measuring the ground footprint and forgetting pitch is how roofs get underbid. Enter the footprint and pitch to get true roof area in squares, bundles including waste, and material cost.
| Input | Value |
|---|---|
| Building footprint area | 2000 |
| Roof pitch (rise per 12) | 6 |
| Waste factor | 12 |
| Bundles per square | 3 |
| Material price per square | 130 |
| Labor per square | 175 |
| Result | Value |
|---|---|
| Roof squares | 22.4 |
| Pitch multiplier | 1.118 |
| Squares to order with waste | 25 |
| Bundles to order | 76 |
| Material cost | $3,255.71 |
| Material + labor | $7,168.83 |
4/12 is 1.054, 5/12 is 1.083, 6/12 is 1.118, 7/12 is 1.158, 8/12 is 1.202, 9/12 is 1.250, 10/12 is 1.302 and 12/12 is 1.414. Multiply the footprint by these to get actual roof surface.
A simple gable roof may only need around 10%, while a roof full of valleys, hips, dormers and skylights can need 15% or more because every cut produces an unusable offcut.
Ridge cap, starter strip, underlayment, ice and water shield, drip edge, valley metal, pipe boots, vents, fasteners, tear-off, disposal and steep or multi-story access charges all sit outside the square count and need their own lines.
100 square feet of roof surface area, measured along the slope rather than on the ground.
Three bundles per square for most standard three-tab and architectural shingles. Heavier designer and laminate products can require four or five, so confirm against the specific product's packaging.
You can measure either, but ground footprint must be multiplied by the pitch multiplier to reach true roof area. Skipping that step underestimates a 6/12 roof by about 12% and a 12/12 roof by more than 40%.
WinkScope's free roofing squares calculator converts building footprint into roofing squares using the pitch multiplier sqrt(rise squared + 144) / 12. One roofing square is 100 square feet of roof surface. A 6/12 pitch multiplier is about 1.118 and a 12/12 is 1.414. The tool adds a waste factor (about 10% for simple gables, 15%+ for cut-up roofs), calculates bundles at typically three per square, and estimates material and labor cost. Free, no signup.