Roofing Calculator – Tiles, Battens, Felt, Materials & Cost
Roofing Calculator
Estimate roof area, tiles or slates, battens, roofing membrane, ridge and hip materials, labour and project costs.
Project Settings
Choose your measurement system, currency and project name.
Roof Dimensions
Add one or more roof sections. Enter horizontal building dimensions and the calculator will use the pitch to determine the true sloping roof area.
⚡ Bulk Roof Section Entry Advanced – quickly enter multiple roof sections ⌄
Tiles / Slates
Enter the manufacturer's coverage rate for the roofing product you plan to use.
Roof Battens
Estimate batten courses, total length and purchasable stock lengths.
Underlay / Felt / Roofing Membrane
Estimate membrane coverage and optional roll quantities.
Ridge, Hip & Verge Materials
These quantities will only be calculated where they apply to the selected roof type.
Optional Verge Materials
Advanced Materials Optional fixings, valleys and additional materials ⌄
Material Pricing Optional – calculate estimated material costs ⌄
Labour & Customer Pricing Optional – estimate labour, markup and VAT / Sales Tax ⌄
Your results will appear below once the Results widget is installed.
Your Roofing Estimate
Enter your roof dimensions and material settings above, then select Calculate Roofing Materials.
Finished Your Roofing Estimate?
Turn your roofing costs into a clean, professional customer quote or invoice with the Handyman Hub Quote & Invoice Generator.
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Roofing Calculator for Tiles, Slates, Battens, Membrane & Materials
The Handyman Hub Roofing Calculator helps estimate the main materials required for pitched roofing projects. It can calculate the true sloping roof area from horizontal dimensions and roof pitch, then estimate tiles or slates, roof battens, roofing membrane, ridge tiles, hip tiles, verge requirements and optional project costs.
It supports both Metric and Imperial measurements and can handle straightforward gable roofs, hip roofs, lean-to roofs and multiple roof sections. For larger projects, the Bulk Roof Section Entry can combine several different roof areas into one overall materials estimate.
How the Roofing Calculator Works
Enter the Roof Dimensions
For a normal pitched roof, enter the horizontal building or roof dimensions together with the roof pitch. The calculator converts the horizontal footprint into the actual sloping roof surface area.
Enter the Roofing Product Coverage
Roofing tiles and slates do not all cover the same area. Enter the manufacturer's tiles or slates per square metre, or the equivalent Imperial coverage rate.
Add Battens & Membrane
Enter the maximum permitted batten gauge for your roofing product and the effective coverage of your roofing membrane or felt rolls.
Get Your Materials Order List
The results combine the different roof sections and create a useful material take-off including purchase quantities and optional costs.
Why Roof Pitch Changes the Roof Area
The horizontal footprint of a building is smaller than the actual surface area of a pitched roof. As the roof becomes steeper, the sloping surface becomes longer and more roofing material is required.
This calculator uses the entered roof pitch to calculate the sloping roof area rather than relying on a simple approximate pitch table. If you do not know the angle of the roof, the calculator also includes a pitch helper using rise and run measurements.
Roof Types Supported by the Calculator
Simple Gable Roof
Suitable for a conventional two-sided pitched roof with a ridge running along the length of the building.
Hip Roof
Suitable for straightforward rectangular equal-pitch hip roofs. Ridge and hip lengths can be estimated automatically.
Single-Slope / Lean-To Roof
Useful for extensions, garages, sheds and other roofs with one continuous sloping surface.
Custom Roof Section
Experienced users can enter an individual roof plane using either horizontal run and pitch or a directly measured sloping length.
Calculating Multiple Roof Sections
Real buildings are not always made from one simple roof. Extensions, garages, porches and additions can have different dimensions and roof pitches.
The Roofing Calculator lets you add individual roof sections or use the Bulk Roof Section Entry for larger projects. Each section is calculated separately before being combined into the overall roof area and materials order.
Complicated roofs with dormers, intersecting roofs, valleys or unusual geometry are normally best divided into several simpler roof sections rather than treated as one large shape.
How Many Roof Tiles or Slates Do I Need?
The number of tiles or slates required depends on the actual sloping roof area and the effective coverage of the chosen roofing product.
Different products can have very different coverage rates because the installed coverage depends on the tile or slate size, headlap, sidelap, gauge and installation system.
For the most reliable result, use the coverage information supplied by the roofing manufacturer rather than assuming every tile or slate covers the same amount of roof.
Roof Area × Tiles/Slates Per Area = Base Quantity
Base Quantity + Wastage = Estimated Order Quantity
How Much Roofing Wastage Should I Allow?
Roofing materials normally require an allowance for cutting, damaged pieces, breakages and unusable offcuts. The correct allowance depends on the shape and complexity of the roof.
A straightforward roof with long uninterrupted slopes may need less wastage than a complicated roof containing hips, valleys, dormers, roof windows and numerous cuts.
The calculator therefore makes the wastage percentage editable rather than assuming one percentage is suitable for every project.
Roof Batten Calculator
Roof batten spacing is controlled by the roofing product and installation requirements. There is no single batten gauge that is correct for every tile, slate or roof pitch.
Enter the maximum permitted batten gauge for the chosen roofing system. The calculator can then estimate batten courses and total batten length, including an optional wastage allowance and purchasable stock lengths.
Roofing Felt & Membrane Calculator
Roofing underlay, felt and breathable membrane normally require more material than the exact roof surface area because of overlaps, trimming and detailing around edges and penetrations.
Enter an overlap or allowance percentage and, if required, the effective coverage of one membrane roll. The calculator will estimate both the total membrane area and the number of full rolls to purchase.
Ridge Tiles, Hip Tiles & Verges
For suitable roof shapes, the calculator also estimates ridge and hip lengths. Enter the effective installed coverage of the ridge or hip tile being used and the calculator will convert the required length into an estimated purchase quantity.
Optional verge unit calculations are also available. Because dry-verge and other verge systems vary, the effective coverage remains user editable.
Estimating Roofing Material & Project Costs
If you only need material quantities, all pricing fields can simply be left at zero.
Tradespeople and contractors can optionally enter costs for roofing materials, battens, membrane, ridge tiles, hip tiles and other items. Labour can be entered using an hourly rate or day rate, together with additional labour or subcontractor costs.
An optional markup can then be applied to the estimated job cost, followed by a user-entered VAT / Sales Tax rate where applicable.
Example Roofing Calculation
Consider a simple gable roof measuring 10 m long by 8 m wide with a 35° pitch.
The horizontal footprint is 80 m², but after allowing for the roof pitch the actual sloping roof area is approximately 97.7 m².
If the chosen roofing product requires 10 tiles per m², the roof would require approximately 977 tiles before wastage. Adding 10% wastage gives an estimated order quantity of approximately 1,075 tiles.
The same roof area can then be used to estimate battens, roofing membrane and other roof materials.
Common Roofing Estimating Mistakes
A pitched roof has a larger surface area than its horizontal footprint.
Eaves and gable overhangs can add a meaningful amount of roof area.
Always use the manufacturer's installed coverage rate where possible.
Cuts and breakages can leave a project short if no allowance is added.
Batten gauge can vary with the roofing product and installation requirements.
Divide extensions and different roof forms into separate sections for a more useful estimate.
Roofing Calculator FAQs
How do I calculate the actual area of a pitched roof?
Does roof pitch increase the amount of roofing material required?
How many roof tiles do I need per square metre?
Can I calculate roof slates instead of tiles?
How much roof tile wastage should I add?
How do I calculate roof battens?
Can this calculator estimate roofing felt or membrane?
Does the Roofing Calculator support hip roofs?
Can I calculate several roofs at the same time?
Does the calculator work in feet and inches?
Can I use this calculator to price a roofing job?
Is this a structural roof design calculator?
Results are estimates for planning and material take-off purposes. Roofing products, fixing requirements, overlaps, batten gauges, installation methods and purchasing quantities can vary. Always check manufacturer specifications and relevant project requirements before ordering materials or carrying out roofing work.