The toolbox / Roofing
Roofing calculators & tools
Calculate roof surface area, shingle bundles, underlayment rolls, plywood or OSB sheathing panels, effective coverage, panel lengths, overlaps, and sheet layouts. Turn measured dimensions and manufacturer specifications into practical material quantities.
Choose a roofing calculator
Check the result and the inputs you haveStart with roof area when you need a sloped surface measurement. If you already have that area, go straight to the material you are estimating. For metal sheets, choose between width coverage, panel length, and a complete rectangular layout.
Start with roof geometry
Roof Area Calculator
Calculate roof surface area and square footage from horizontal dimensions, plan area, measured sloped area, and roof pitch.
- Have ready
- Horizontal roof dimensions or plan area and pitch, or an area already measured on the slope.
Asphalt shingle bundles
Roof Shingle Calculator
Calculate roofing squares and whole asphalt-shingle bundles from roof area, allowance, and manufacturer packaging.
- Have ready
- Sloped roof area or a simple outline and pitch, the selected product’s bundle coverage, and your allowance.
Plywood or OSB panels
Roof Sheathing Calculator
Calculate whole plywood or OSB roof-sheathing panels from roof area, pitch, panel dimensions, and a user-selected allowance.
- Have ready
- Sloped roof area or a simple outline and pitch, panel length and width, and your allowance.
Underlayment rolls
Roof Underlayment Calculator
Calculate whole roof-underlayment rolls from sloped roof area, project layers, manufacturer coverage, and a chosen allowance.
- Have ready
- Sloped roof area, the project’s layer count, effective coverage per roll after applicable laps, and your allowance.
Sheets across one row
Roof Sheet Effective Width Calculator
Use a published roof-sheet cover width or derive it from the overall width and side lap, then calculate sheets per row.
- Have ready
- Roof width across the sheets, plus published cover width or overall sheet width and side lap.
Panel length along a slope
Metal Roof Panel Length Calculator
Calculate metal roof panel length from horizontal run and pitch, including eave extension, ridge setback, and optional end laps.
- Have ready
- Horizontal eave-to-ridge run, rise or pitch, eave extension, ridge setback, and any panel-count or end-lap details.
Sheet rows, columns and cuts
Roof Sheet Calculator and Layout Planner
Calculate metal roof-sheet rows, columns, cut sizes, stock quantity, retained overlap material, and offcuts for one rectangular slope.
- Have ready
- One rectangular slope’s dimensions and pitch, sheet cover and stock dimensions, and project lap details.
Roofing guides
Understand the measurements used by the toolsMeasurement guide
How to Measure Roof Pitch
Measure rise over a horizontal run using accessible framing, verified dimensions, or an angle reading, then continue into pitch conversion and roof calculations.
Reference guide
Roof Pitch Chart
Convert rise per 12 into degrees, percentage slope, slope factor, and sloped length, then continue into roof-area or panel-length calculations.
Selection guide
Types of Roofing Sheets
Compare material groups and panel profiles, then identify the exact product dimensions needed for roof-sheet calculations.
Material comparison
Synthetic vs Felt Underlayment
Compare product requirements, effective roll coverage, and whole-roll material costs before estimating your underlayment order.
Plan the takeoff
Start with roof geometry, then select the material workflow
If the pitch is unknown, begin with the roof pitch measurement guide. Use the Roof Pitch Chart when drawings or measurements use a pitch, angle, percentage, or slope factor that needs interpretation. If the covering has not been selected, compare the types of roofing sheets and obtain the exact product dimensions. Then calculate the sloped roof area or panel length before applying product coverage, laps, package rounding, or a user-selected allowance.