Roof Area Calculator
A pitched roof’s real surface is larger than its footprint — the steeper it is, the more material it takes. Enter the plan size and pitch to get the true (sloped) roof area you actually buy tiles, sheets, underlay, waterproofing and insulation for — in m² and sq ft, with a wastage allowance.
Slope factor 1 / cos(22°) = 1.079 — the roof is 8% bigger than the footprint.
Allows for cuts, overlaps, ridges & hips. 5–10% for simple roofs, 10–20% for complex ones.
= 1,379 sq ft · incl. 10% wastage.
Indicative only — pick the row that matches your roof. Tile and sheet sizes vary by product; confirm coverage from the maker’s data.
A planning estimate. It treats the roof as a simple plane at the pitch you set, scaled by the slope factor 1 / cos(pitch). Real roofs have hips, valleys, dormers, overhangs and varying pitches, and material coverage differs by product — so take off actual quantities from the drawings before ordering. Structural design and any work at height are for a qualified engineer and roofing contractor.
Related Guides — Deep-dive reading
Roof Construction Cost in India
What a roof actually costs to build in India, honestly and with ranges — the cost drivers, indicative 2026 rates per sq ft and per m² for RCC, tiled, metal and sheet roofs, what is included versus commonly extra, how city and climate move the number, hidden costs and lifecycle value. Plain language, India-grounded.
RoofingRoofing BOQ & Tender: Measuring, Pricing and Comparing Quotes in India
How to prepare a roofing Bill of Quantities and run a fair tender — the item breakdown, measurement basis and units, rate analysis, wastage and overlap allowances, measurable item descriptions tied to the spec, and how to evaluate bids on best value, not just lowest price.
RoofingRoofing for Coastal & Saline Areas
Within a few kilometres of the sea — Chennai, Mumbai, Goa, coastal Kerala, Vizag, the Konkan — salt-laden air makes corrosion the roof's relentless enemy. A plain-language guide to materials, fasteners, coatings and upkeep that survive the coast.
RoofingRelated Tools — You may also find these useful
Rainwater Harvesting Calculator
How much rainwater your rooftop can harvest in a year, in litres and kilolitres, from the roof area, your city's rainfall and roof type — with a suggested storage-tank size.
RoofingRoof Cost Calculator
An indicative cost range to build a roof in India, by roof type (RCC, tiled, metal, sheet), area, waterproofing, insulation and city — total and per sq ft. A budgeting frame to confirm with local quotes.
RoofingRoof Heat Gain Calculator
How much heat your roof lets in and how much insulation cuts it — heat gain in watts and the AC tonnage it adds, from roof construction (U-value), area and temperature difference, versus a bare slab.
Roofing