Arithmetic resultCanada-wide arithmetic

Roofing Materials Calculator

Estimate sloped roof area and product quantities for a simple roof footprint. No snow-load or member-sizing advice.

Free tool — no sign-up needed. Your numbers stay on this device until you export or share them.

My plan

My renovation plan · Toronto, Ontario

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01 · Project measurements

Adjust the inputs and the result updates immediately.

Example numbers — replace them with your room.

Roof footprint lengthmRoof footprint widthm

Pitch risePitch run

Waste allowance%Editable default

Technical assumptions

Bundle coveragem²Editable defaultUnderlayment roll coveragem²Editable default

02 · Planning result

Source-backed method

Order area

77.56 m²

Roof footprint

66.89 m²

Pitch multiplier

1.05

Net sloped area

70.51 m²

exact size, no waste added

Roofing squares

8.35

Bundles

Underlayment rolls

More actions

Private web sharing: Available after secure cloud save is released

Assumptions

These are part of the result, not fine print.

The roof is modelled as one simple pitched footprint without dormers, valleys or hips.
Editable waste allowance: 10%
Entered coverage per bundle: 3.0967680000000004 m²
Entered coverage per underlayment roll: 37.161216 m²

Quantity only: this result does not assess structure, snow load, ventilation, membranes or code compliance.
Product counts use the entered package coverage; verify each manufacturer label.

Planning information only. This is not a quote, code-compliance decision, structural recommendation, or substitute for site review.

Government of Canada, Department of Justice

Canadian SI, yard, foot, inch, area and volume unit definitions

Version: current-to-2026-06-14CanadaR.S.C., 1985, c. W-6; page current to 2026-06-14Source-backedLast reviewed: 2026-08-01

Orion Project Studio

Geometry-only material quantity calculation contract

Version: 1.0.0Canada1.0.0Source-backedLast reviewed: 2026-08-01

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