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Online Roofing Calculator
Roofing Calculator estimates roof area and the shingles, roll roofing, and felt you'll need from your house size and roof pitch — no signup.
Roofing
The estimated roof area in square feet: 2,818
The estimated roof area in square meter: 261.8
The estimated roof area in square yard: 313.1
Required roof squares to have 10% buffer:31
By United States standard, the roof will need:
85 bundles of composition shingles (each bundle will cover ~33 ft²)
29 rolls of roll roofing (~36 in × 36 ft for each roll)
8 rolls of #15 felt (~36 in × 144 ft for each roll)
15 rolls of #30 felt (~36 in × 72 ft for each roll)
Roofing
Required roof squares to have 10% buffer: 25
By United States standard, the roof will need:
85 bundles of composition shingles (each bundle will cover ~33 ft²)
29 rolls of roll roofing (~36 in × 36 ft for each roll)
8 rolls of #15 felt (~36 in × 144 ft for each roll)
15 rolls of #30 felt (~36 in × 72 ft for each roll)
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What Is This Tool?
The Roofing Calculator estimates how much roof you have and the materials needed to cover it. On the main tab you enter your house base area, how far the eaves overhang, and the roof's steepness as either a pitch or an angle; it then models a simple gable roof and reports the estimated roof area in square feet, square meters, and square yards, plus the number of roofing squares with a 10% waste buffer. It also estimates US-standard materials — bundles of composition shingles, rolls of roll roofing, and 15# and 30# felt. A second tab skips the geometry and returns those material counts directly from a roof area you already know. You can switch between metric and imperial units and download the result as a PDF.
How to Use This Tool?
- On the Roofing tab, enter your house base area and how far the eaves stick out.
- Choose pitch or angle and set the roof's steepness.
- Click Calculate to see the estimated roof area, roofing squares, and material counts.
- Or use the Roofing Material tab to get material counts straight from a known roof area.
Key Features
- Two modes: estimate roof area from house base area, eave overhang, and pitch or angle, or get materials from a known roof area.
- Reports estimated roof area in square feet, square meters, and square yards.
- Calculates roofing squares with a built-in 10% waste buffer.
- Estimates US-standard materials — composition shingle bundles, roll roofing, and 15# and 30# felt rolls.
- Metric/imperial toggle and one-click PDF download of the results.
Examples
- A 204.38 m² base with 0.4572 m eaves at a 6/12 pitch returns about 261.8 m² (2,818 sq ft) of roof.
- That same roof works out to roughly 31 roofing squares once the 10% buffer is added.
- It estimates about 85 bundles of composition shingles for that area.
- Entering a known roof area of 204.38 m² on the second tab skips the geometry and returns material counts directly.
Common Use Cases
- Budgeting a reroofing project before getting contractor quotes.
- Estimating shingle and underlayment quantities for a material order.
- Sanity-checking a roofer's material list.
- Planning DIY roof repairs or replacements.
- Converting a known roof area into standard roofing squares.
Tips & Best Practices
- Measure your house's footprint area as accurately as possible, since the estimate scales directly from it.
- Include the eave overhang so the roof area isn't undersized.
- Match the pitch (rise over 12) or the angle to your roof's actual slope.
- Order to the buffered roofing-squares figure to allow for waste and cuts.
- Use the Roofing Material tab when you already know the true roof area for a tighter estimate.
Limitations
- It approximates a simple gable roof from your base area, not the exact shape of complex or multi-section roofs.
- Material counts follow US-standard coverage rules and may not match every product or local supplier.
- The price field is shown but isn't applied to the results, so no cost total is produced.
- Nothing is saved between sessions — only the current result can be exported as a PDF.
Frequently Asked Questions
- How does it estimate roof area from just the base area?
- It models a simple gable roof, scaling your footprint by the eave overhang and the pitch or angle you choose.
- What is a roofing square?
- A roofing square equals 100 square feet of roof; the tool rounds up and adds a 10% buffer for waste.
- Can I enter measurements in feet instead of meters?
- Yes — the metric/imperial switch converts your inputs automatically.
- Does it calculate the cost?
- No. There is a price field, but the current version doesn't apply it to produce a total.
Key Terminology
- Roof pitch
- The roof's steepness, given as inches of rise per 12 inches of horizontal run, such as 6/12.
- Eaves overhang
- How far the roof edge extends beyond the house wall.
- Roofing square
- A unit of roof area equal to 100 square feet.
- Composition shingles
- Standard asphalt shingles sold in bundles, several of which cover one roofing square.
- Roofing felt
- Underlayment laid beneath the shingles, offered here in 15# and 30# weights.