Roofing Calculator
Estimate shingles, roofing squares, bundles, waste, underlayment, tear-off, and project cost from roof footprint and pitch.
Build Your Roofing Order
Remove old shingles and install new — most common
Most common US roof pitch — balanced look
If you do not know the pitch, the safest shortcut is measuring from inside the attic or checking plans you already trust.
Most popular — textured, thicker, wind-resistant
Order Summary
Quantity checks
Accessory counts on this page are planning quantities for a straightforward residential roof, not a full multi-plane takeoff.
Roof replacement notes
- Footprint area is 1,200 sq ft before pitch is applied.
- 6/12 pitch uses a factor of 1.118, which brings the roof area to 1,341.6 sq ft.
- This project type includes tear-off, so the budget is closer to a real reroof number than a materials-only estimate.
This page starts with the house footprint, then turns that base area into a real roofing order before you compare worked examples.
Worked examples
Standard reroof
30 ft x 40 ft footprint · 6/12 pitch · architectural shingles
This is the most common roofing order: reroofing a standard home with architectural shingles, tear-off, and a normal waste factor.
Steeper replacement roof
28 ft x 50 ft footprint · 8/12 pitch · premium shingles
As the roof pitch climbs, the material count rises and labor usually follows. This is where pitch stops being a side note and starts driving the order.
Metal roof project
24 ft x 36 ft footprint · 5/12 pitch · metal roofing
Metal roofing changes the buying language. You stop thinking in bundles and start pricing the job more like square coverage plus accessories.
Where roof orders usually change
Simple gable roof
Straight ridges and fewer cuts keep the order close to the base square count plus a normal waste rule.
Hip roof or multiple ridges
More ridge length means more cap bundles and more cut pieces, even before the footprint looks much bigger.
Dormers, valleys, and cut-up roofs
Complex intersections burn material in cuts and often push the real order above a simple footprint estimate.
How to use this calculator
- Measure the footprint first. Start with roof length and width at the footprint level. For many homeowners, that is easier than trying to measure every roof plane directly.
- Pick the pitch. Pitch is what turns flat footprint area into real roof coverage. That is why two homes with the same base area can need different amounts of roofing.
- Choose the project type. A reroof with tear-off is a different budget from a simpler install path, so this should be set before you trust the cost number.
- Select the material. Bundles matter for shingles, while metal jobs are still bought by square coverage and accessories.
- Read the order summary. Start with squares, then bundles, then the supporting materials and budget.
How we calculate
Example: 30x40 ft roof at 6/12 pitch
- Footprint = 30 x 40 = 1,200 sq ft
- 6/12 pitch factor = 1.118
- Roof area = 1,200 x 1.118 = 1,341.6 sq ft
- Roofing squares = 1,341.6 / 100 = 13.4
- With 10% waste, order rounds to about 15 squares
Why pitch matters
A steep roof covers more actual surface area than its flat footprint suggests. That is why roofing pages need pitch right in the main calculation, not tucked away in a note.
Pitch factors and roof replacement planning align with standard residential roofing estimating practice for squares, bundles, and accessory counts.
This estimate starts from the roof footprint. Wide eaves, complex roof lines, valleys, and multiple planes can push the actual order higher than a simple footprint-based estimate.
Measure without climbing
Footprint from plans or exterior walls
Best for fast first-pass ordering. Measure the building footprint, then let pitch convert that base area into roof coverage.
Pitch from attic or trusted plans
This is safer than climbing. One good pitch number improves the square count more than guessing from the driveway.
Complexity from the ground
Count valleys, dormers, and ridge changes before you trust a low waste number. Roof shape changes the buy list.
Pitch factor guide
4/12 and below
Lower-slope roofs usually need more care around underlayment and water management. They also make ice-and-water protection more relevant.
5/12 to 7/12
This is the common residential zone. It is still easy enough to explain to homeowners and usually where standard replacement jobs sit.
8/12 and above
Steeper roofs increase labor difficulty fast. Even when the footprint stays the same, material area and labor risk both rise.
Material choice guide
3-tab shingles
Lowest upfront material cost
Best when budget is the main driver, but not usually the longest-lasting choice.
Architectural shingles
Most standard roof replacements
This is the usual middle-ground answer for homeowners who want a better look and longer warranty without jumping to metal.
Premium shingles
Higher-end curb appeal
These make sense when appearance and warranty matter more than the tightest upfront budget.
Metal roofing
Long life and lower maintenance
The buying language changes here because you are no longer thinking in bundles, but the total square coverage still drives the order.
Tear-off and waste guide
Tear-off included
A reroof usually needs tear-off in the real world. It adds cost, but it also gives you the chance to inspect the deck before the new roof goes on.
Roof-over caution
Layering over the old roof can cut labor, but it is not the right fit for every structure or code situation. This page keeps the estimate focused on the more standard replacement path.
Waste and roof complexity
Simple gable roofs stay closer to the normal waste rule. Valleys, dormers, hips, and complicated cuts usually push the order higher.