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Rainfall Runoff Volume Calculator

Estimate runoff volume from rainfall depth, contributing area, and a user-selected runoff coefficient.

Inputs

Range: at least 0 sq ft

Measure the roof, paving, or other contributing surface included in this estimate.

Range: at least 0 in

Use a stated storm depth for the event being evaluated; this tool does not select a design storm.

Range: 0–1

Choose a coefficient supported by the surface/site method or project guidance; no universal value is assumed.

Result

Gross rainfall volume (cu ft)
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Estimated runoff volume (cu ft)
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Estimated runoff volume (cu yd)
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Estimated runoff volume (gal)
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Estimate scope
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