Roof area and materials calculator
Estimate roof area from footprint or planes
Use plan length, width and one uniform pitch for a simple roof, or measure up to four planes. Add product rates only from exact data.
Roof area and covering estimate
Use a uniform-pitch footprint estimate for a simple roof or enter each plane separately. Product rates must come from the exact manufacturer's data for your pitch and exposure.
- Whole-roof plan area
- m²
- Net sloped roof area
- m²
- Rounded area by plane
- Measurement method
- Area with entered waste
- m²
- Net field tiles
- Field tiles with entered waste
- Whole packs
- Field tiles in full packs
- Extra field tiles from pack rounding
- Selected product data
- Pitch and roof-length check
- Net batten length
- linear m
- Membrane rolls at entered usable coverage
- Marley Universal HipFast boxes (length-only minimum)
- Marley Universal RidgeFast boxes (roll-length minimum)
Method and limits
Model version: 2026-09-25-v9
- Plane mode sums each plane's eaves length × horizontal run ÷ cos(pitch). Whole-footprint mode uses plan length × plan width ÷ cos(uniform pitch) and only applies to a rectangular roof with one pitch.
- Plane mode accepts one to four planes. Footprint mode assumes a rectangular outline and one uniform pitch; neither detects overlaps, dormers, valleys or roof openings.
- Custom tile and batten quantities use the exact rates you enter. The optional Marley preset applies only to its four listed finish/headlap configurations and requires plane mode for its length checks.
- A preset flags pitches below the manufacturer's listed minimum. A quantity calculation is not a roof design or compatibility approval.
- Marley says special circumstances can affect minimum pitch and recommends technical advice for slopes over 6 m or severe exposure.
- Pack output includes the number of tiles in whole packs and the surplus over the entered order quantity.
- Membrane rolls use the usable coverage per roll that you enter after overlaps.
- The optional HipFast result divides combined measured hip length by the published 6 m roll per box and rounds up. It is a length-only minimum, not a sufficient kit order or a compatibility check; junctions, cuts, waste and product details can change the quantity.
- The optional RidgeFast result separately divides measured ridge length by the published 6 m roll per box and rounds up. It is a roll-length minimum, not a full accessory schedule; check tile profile, pitch limits, junctions, cuts and waste with Marley.
- Other fittings, fixings, structural checks and a fixing specification are excluded.
What brought you here?
I need the roof area
Use plan length, width and one uniform pitch for a simple roof, or measure each plane separately. The result is sloped area.
I know the product
Choose a supported Marley tile preset or enter coverage, batten rate and membrane coverage from the exact product data sheet.
I am comparing quotes
Compare the written scope, access, VAT and exclusions alongside the total. A material estimate is not a roof survey.
What happens next
- Measure the roof outline or each plane without walking on the roof
- Convert the plan area or each run and pitch into sloped area
- Add product rates only from the chosen specification
- Confirm fittings, waste and access before ordering
Three useful starting points
- Roofing calculator: area, tiles and battensEstimate a simple roof from plan dimensions and uniform pitch, or add up to four measured planes; material rates remain product-specific.
- Roof tile coverage, gauge and headlapWhy tiles per square metre depends on the product and laying details, with a dated manufacturer example.
- Roof measurement and quote checklistRecord roof planes, product data, access questions and exclusions before comparing roofing estimates.
Decision guides
This site estimates geometry and quantities. It does not inspect roofs, specify products, quote work or recommend a roofer.
Open the roofing calculator