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Roofing Calculators Plan roof replacement ranges and gutter sizing inputs with transparent, project-specific assumptions.
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Choose a calculator 2 planning tools available.
Available
Planning arithmetic only — not a gutter/downspout design or code result. This tool converts the tributary catchment area, runoff coefficient, design rainfall intensity, and per-unit capacities you enter into a peak design flow and a whole capacity-unit count. It does not look up or approve rainfall, survey roof geometry, choose a runoff coefficient, verify manufacturer capacity, or design gutter profile/slope/length, outlets, downspout spacing, elbows, restrictions, fasteners, debris/ice allowance, maintenance, primary/secondary overflow, ponding or structural rain load, underground piping, detention/infiltration, grading, erosion control, or discharge. Verify local code and stormwater/property rules, approved discharge location, foundation and neighboring-property impacts, manufacturer data, and the complete route to a lawful receiving point. Use a qualified drainage/building professional and the authority having jurisdiction for consequential work. It reports capacity units needed at the entered per-unit capacity.
Open calculator Available
Plan roof replacement area and a cost range from explicit geometry, pitch, waste, rates, and named allowances.
Open calculator Plan with transparent assumptions Use each result as a planning estimate. Confirm project requirements, product instructions, local conditions, and professional or permit needs before purchasing materials or starting work.
