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Rational Method Calculator

Calculate peak stormwater flow using rational method.

Surface area measurement (length × width for rectangles).
acres
A numerical factor used in formulas.
Enter the rainfall intensity value for this calculation.
in/hr
Proportional relationship between two values.
min

Results

Peak Flow:
Calculated flow rate.
-cfs
Peak Flow:
Calculated flow rate.
-GPM
1-hr Runoff Volume:
Calculated three-dimensional space.
-ft³
Reference: AWWA/EPA Standards. Rational method Q=CiA.