Roof Area and Material Pack Calculator
Calculate uniform-pitch roof surface area and coverage packs for a rectangular footprint.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Expand the horizontal footprint for overhangs and multiply by the uniform slope-area factor.
Roof area=(L+2o)(W+2o)√[1+(rise/run)²]; packs=ceil[area×(1+allowance)/coverage]
Worked example
A 10 m × 8 m horizontal footprint without overhang and a 6:12 pitch has about 89.4427191 m² of sloped surface. At 3 m² per pack and 10% allowance, 33 packs are needed.
Assumptions and input details
Rise and run are a dimensionless ratio expressed in the same length basis, not an angle in degrees. The simple mono-pitch or gable roof has uniform pitch and rectangular footprint; hips, valleys, dormers, openings and ridge/starter products need separate allowances. Enter product coverage and waste yourself. No site price, roof access advice or structural design is supplied.
References: GAF: roof area, slope and complexity factors
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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