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BUILT FOR ROOFING

Roofing calculator.

Work out the area. Find the quantities. Know the cost.

Free to use No signup needed Calculations in your browser
Results update as you type
Roof area

Calculate your roof surface area

From a flat plan or an area you have already measured.

Start with what you know

Choose whether your measurements are flat or already sloping.

Use the full footprint for the section, not just one rafter run.

Add the roof pitch

We use this to turn flat plan area into sloping roof area.

How is your pitch measured?

Angle of the roof above horizontal. 0° is flat.

Your calculations stay in this browser tab.
YOUR CALCULATIONLive preview
Roof surfaceDashed outline = flat footprint
Roof surface area
—m²

Enter width, length to see your result.

Planning estimate · verify before ordering

These tools calculate geometry and estimate quantities. They do not assess structural suitability, fixing schedules or manufacturer requirements.

A LITTLE CLARITY GOES A LONG WAY

Know what goes into your numbers.

The calculator keeps the working visible, so you can check your measurements and make an informed next step.

What is the difference between plan area and roof surface area?

Plan area is the flat footprint viewed from above. Roof surface area is measured along the slope. For one pitch, surface area = plan area ÷ cos(pitch). Choose “Already measured” when your value already includes the slope; no second pitch factor is applied.

Do I enter the full width or half the width?

For Roof area, enter the full plan width and length of the section you want to calculate. For Rafter length, enter the horizontal run from wall to ridge. On a symmetrical gable, that run is half the building width. Include overhangs only where your chosen measurements include them.

Does the result include waste?

Roof area and rafter / hip lengths do not include waste. Battens include the waste percentage you enter. Material pricing applies your selected waste rule before pricing. Transferring a batten total into pricing switches additional waste off to avoid counting it twice.

Can I use feet and inches?

Yes. Switching to Imperial converts existing measurements instead of just changing their labels. Lengths use feet, areas use square feet, and batten gauge uses inches. Per-unit material rates also convert. Currency selection changes the currency label only; it is not an exchange-rate conversion.

How should I handle a roof with different pitches?

Calculate each differently pitched section separately, then add its surface area to your estimate. The hip / valley length mode assumes equal roof pitches at a 90° plan corner. Junction allowances, penetrations and material coverage requirements need to be assessed separately.

Can I turn these measurements into a quote?

Use “Add to a free quote” to transfer a measurement, or price it first and use “Create a free quote” to transfer material and labour line items. Review tax, margins and your customer details in the Quote Generator. These calculator estimates do not include tax or profit margin.

Do I need to create an account?

No account is required for calculations, copying or downloading results. Your working inputs are kept in session storage in this browser tab where available. Saving a Smart Component to QuoteCore+ sends the draft to the app and requires the appropriate paid workspace; it is a separate, optional action. The site’s normal authentication and analytics remain in place.

FROM A MEASUREMENT TO A WORKFLOW

There’s more to a job than the numbers.

See how the paid QuoteCore+ app connects digital takeoff, Smart Components, quotes, orders and invoices. Start with the demo, without signing up.

Try the Demo Explore QuoteCore+