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Roof Area, Sheet and Tile Calculator

Start with sloped roof area, then choose a specific covering before counting materials.

Starting values are examples. Adjust them for your project.

Measure along the lower edge of one roof face, usually the gutter line.

Use a plan or roofer measurement; do not climb onto a roof to measure it.

Number of rectangular faces with these same dimensions. Calculate unequal faces separately.

Material and detailed settings

See how the calculation works

Enter your details to see the drawing.

Edit measurements ↑ Measurements and worked example ↓

Your diagram

Roof area and covering materials guide

Start with sloped roof area without choosing a product. To count sheets or tiles, first choose a product and obtain its installed coverage from the manufacturer.

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Measure and prepare

Where to find the eave, ridge and slope measurement Ridge · top joinA · Eave / lower edgeB
A: measure along the lower edge, usually where the gutter runs. B: measure down the sloping surface from the top edge to the lower edge. This diagram identifies the parts; it does not represent your roof dimensions.

The eave is the lower roof edge, usually where the gutter runs. The ridge is the highest line where two sloping roof faces meet. Measure the length along the eave, then the slope length along the roof surface from ridge to lower edge; slope length is not the horizontal distance shown on a floor plan.

Sketch each simple rectangular roof face and note its eave and slope lengths. Calculate faces of different sizes separately. Mark penetrations, skylights and hips on the sketch before ordering because special pieces and cuts can change demand.

How the estimate works

Area mode multiplies eave length × measured slope length × equal faces; it also reports the measured slope. Material mode counts sheets by rounding up eave length divided by installed cover width per face, then adds extras. Tiles use sloped area × the chosen product’s installed tiles per m², plus extras.

In sheet mode, 6 ÷ 0.76 = 7.89, rounded to eight sheets per face. Two faces need 16; 10% extra gives 17.6, rounded to 18. In tile mode, sloped area is 6 × 4 × 2 = 48 m². An illustrative rate of 10 installed tiles/m² gives 480 tiles; 10% extra gives 528.

Check the order

For sheets, confirm installed cover width and slope-spanning length. For tiles, confirm tiles per m² at the actual pitch and batten gauge because overlap changes coverage. Order ridge, verge and special pieces separately.

For sheets, request the exact installed cover width, available cut lengths, lap and minimum pitch from the manufacturer. For tiles, use the tiles-per-m² figure at the intended batten gauge and pitch. Make a separate list for ridge and verge pieces, starter/end tiles, fasteners and weatherproofing accessories.

Limits of the estimate

Measured slope length is not an order length for sheets; end details, lengthwise laps and fixing depend on the chosen system. The tool does not design structure, wind resistance, roof openings or complex hips. Have a roofer check the layout before ordering.

The default treats two roof faces as equal and does not design battens, loads or wind resistance. Similar-looking tile profiles can have very different installed coverage. Do not turn the initial rate into a purchase order without the exact profile data and an installer-reviewed roof layout.

Common questions

Can I use nominal sheet width?

No. Use installed cover after side lap.

Is tile coverage constant for every roof?

No. Use the chosen model’s rate at the selected pitch and batten gauge.

Are ridge pieces and fasteners included?

No. List them for the chosen roof system separately.

Sources and calculation guidance

Check these against your chosen product’s label and instructions.

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