Essential Tools

Fundamental calculators for common drainage problems. Start here for basic pipe sizing, runoff estimation, and inlet design.

12 Calculators

Hydrology

Estimate runoff and calculate travel times

Calculate peak discharge using Q = CiA for small watersheds

Calculate runoff depth using the NRCS curve number method

Look up C values for the Rational Method

Calculate Tc using Kirpich, FAA, and NRCS methods

Analyze pipe and channel flow capacity

Calculate pipe flow capacity and velocity using Manning's equation

Calculate open channel flow for various cross-section shapes

Size inlets, drains, and building drainage

Size storm drainage inlets and sediment storage

Calculate inlet efficiency using HEC-22 methods

Calculate gutter capacity, spread width, and velocity

Size subsurface drainage systems

Size downspouts using IPC tables

Size primary and overflow roof drains

Looking for more advanced tools?