Tile drain, waterway, and drainage design tools. Browse our free drainage tools below — all calculators are instant, accurate, and require no sign-up.
Drain Tile Size Calculator — Calculate the required drain tile pipe diameter from drainage area, drainage coefficient, and pipe slope using Manning's equation for agricultural tile design.
Drainage Coefficient Calculator — Calculate the drainage coefficient (DC) in inches per day needed to remove excess water from agricultural fields. Size tile drains and surface systems.
Terrace Spacing Calculator — Calculate agricultural terrace spacing from land slope, soil type, crop type, and management practice. Reduce erosion with properly spaced terraces.
Retention Pond Sizing Calculator — Calculate the required retention pond volume from storm depth, drainage area, and runoff coefficient. Size stormwater retention for agricultural and rural sites.
Grassed Waterway Design Calculator — Calculate the design flow for a grassed waterway using the Rational Method from drainage area, rainfall intensity, and runoff coefficient.
Tile Drain Spacing Calculator — Calculate tile drain spacing using the Hooghoudt equation from soil hydraulic conductivity, drain depth, and drainage coefficient for farm fields.