HTHOMETALLYTHE PRACTICAL HOME GUIDE

Construction/ CALCULATOR

Roof covering area and pack estimate

Convert a simple horizontal roof footprint and pitch into sloping area, order area and whole packs.

Use the plan length covered by this consistent roof system.
Use the full horizontal footprint for a simple equal-pitch roof.
Use the verified pitch angle, not a visual estimate.
Subtract only the true uncovered area; curbs and flashing still require material.
Set from roof shape, sheet or tile module, laps and supplier guidance.
Use effective installed coverage after product laps, not raw sheet dimensions.
Horizontal plan area

80.00 m²

Gross sloping roof area

92.38 m²

Net covering area

90.38 m²

Area including allowance

99.41 m²

Estimated whole packs

42 packs

Effective coverage in whole packs

100.80 m²

A simple roof whose entire horizontal footprint has one entered pitch. Hips, valleys, dormers, unequal pitches, overhang changes, ridge and verge pieces, flashing, underlay, battens, fasteners, product layout and structural requirements need separate measurement. Declared pack coverage must already account for normal product laps.

FROM ESTIMATE TO ACTION

Use the result, not just the number.

01

Verify the inputs

Measure or document each input. If a value is only an estimate, record its source and test a conservative alternative.

02

Keep the calculation traceable

Save the input link or copied result together with the date, units and assumptions. A number without its inputs cannot be checked later.

03

Confirm the decision

Compare the estimate with the related guide, current product data and requirements that apply at your location before buying or building.

Inputs to verify

Horizontal roof length (m)
Use the plan length covered by this consistent roof system.
Horizontal roof width (m)
Use the full horizontal footprint for a simple equal-pitch roof.
Roof pitch (°)
Use the verified pitch angle, not a visual estimate.
Net excluded roof openings (m²)
Subtract only the true uncovered area; curbs and flashing still require material.
Cutting and handling allowance (%)
Set from roof shape, sheet or tile module, laps and supplier guidance.
Declared effective coverage per pack (m²/pack)
Use effective installed coverage after product laps, not raw sheet dimensions.

Continue your calculation

Construction

Roof pitch and slope length

Convert a measured rise and horizontal run into pitch angle, slope percentage and sloping length.