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Online Roofing Calculator
Calculate the area of flat or pitched roofs and estimate the number of shingle bundles needed accurately with our easy-to-use roofing calculator.
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?
This online roofing calculator helps determine the total surface area of your roof based on its dimensions and pitch. It also estimates the number of shingle bundles required for installation or repair, making it an essential tool for homeowners, contractors, and builders.
How to Use This Tool?
- Enter the roof length (l) and width (w) in feet
- Specify the roof pitch as the rise over run ratio or choose a common pitch multiplier
- For flat roofs, the calculator uses the basic area formula: A = l × w
- For pitched roofs, the tool applies the multiplier: A = (l × w) × M
- Calculate the total roof area and then estimate the number of shingle bundles needed
- Review results and adjust inputs as necessary for accuracy
Key Features
- Calculates flat or low-slope roof area using length and width inputs
- Adjusts roof area for pitched roofs with pitch multiplier formulas
- Estimates the required shingle bundles based on standard shingle coverage
- Supports common pitch ratios with predefined multiplier values
- Provides precise material requirements to assist in budgeting and planning
Examples
- A 40 ft by 30 ft roof with a 6/12 pitch: Base area = 1200 sq ft, Pitch multiplier = 1.118, Total area = 1341.6 sq ft, Bundles needed = 41 bundles after rounding
- For a flat roof measuring 50 ft by 20 ft: Area = 1000 sq ft, Shingle bundles required = 31 bundles
- Using an 8/12 pitched roof with dimensions 35 ft by 25 ft: Area = (35 × 25) × 1.202 = 1051.75 sq ft, Bundles needed = 32 bundles
Common Use Cases
- Estimating roofing material quantities before starting repairs
- Helping contractors provide accurate quotes for roofing projects
- Assisting homeowners in planning roof installations and budgeting
- Calculating coverage for roof renovations or replacements
- Preparing material orders for efficient procurement and inventory management
Tips & Best Practices
- Double-check roof measurements for highest accuracy
- Select the correct pitch multiplier or use the rise/run ratio when available
- Round up the number of shingle bundles to allow for waste and overlaps
- Use this tool as a guide; adjust for complex roof shapes manually
- Consult with a roofing professional for complicated roof geometries
Limitations
- Calculations assume simple rectangular roof shapes only
- Does not account for complex roof elements such as valleys, dormers, or hips
- Manual adjustments are necessary for roofs with multiple planes or irregular shapes
- Shingle bundle estimates are based on standard coverage and may vary by product
- Not intended for designing or engineering roofing structures
Frequently Asked Questions
- Can this calculator handle roofs with multiple pitches?
- This tool calculates roofing area for simple roof geometry with a single pitch. For multiple pitches, calculate each section separately and sum the areas manually.
- How is the pitch multiplier determined?
- The pitch multiplier is calculated using the formula M = √(1 + (rise/run)²) which adjusts the flat roof area based on roof steepness.
- What if my roof pitch is not one of the common ratios listed?
- You can manually enter the rise and run values to compute the correct pitch multiplier using the given formula.
- Why do I need to round up the number of shingle bundles?
- Rounding up accounts for waste, overlaps, and any errors during installation ensuring you have enough material.
- Is this tool suitable for commercial roofing projects?
- Yes, it can be used for both residential and small commercial projects; however, complex commercial roofs may require more detailed calculations.
Key Terminology
- Roof Length (l)
- The horizontal measurement of the roof from end to end.
- Roof Width (w)
- The horizontal measurement perpendicular to the roof length.
- Rise/Run
- The ratio that defines the pitch or slope of the roof.
- Pitch Multiplier (M)
- A factor used to adjust the flat roof area to account for the roof slope.
- Total Roof Surface Area (A)
- The overall roof surface measurement calculated using length, width, and pitch.
- Shingle Bundles
- Standard packaging units of shingles, each covering about 33 square feet.