Hydrology Formulator

HYDROLOGY FORMULATOR is the ultimate pocket reference for hydrologists, civil
engineers, environmental scientists, and students. Packed with 1,000+
formulas, calculators, and conversions, it covers everything from groundwater
analysis to stormwater design — all in one powerful app.

HYDROLOGY CALCULATORS

Infiltration & Recharge — 17 Calculators
- Porosity, Green-Ampt Infiltration, Horton Infiltration, Philip Infiltration,
Holtan's Model, Hydraulic Conductivity, Groundwater Recharge, Mean Pore
Velocity, Specific Discharge, Volumetric Water Content, and more

Evaporation & Transpiration — 8 Calculators
- Penman-Monteith ET0, Blaney-Criddle ET, Thornthwaite PET, Crop
Evapotranspiration, Saturation Vapor Pressure, Evaporation Rate of Lake,
Relative Humidity, Potential Evapotranspiration

Open Channel Flow — 12 Calculators
- Manning's Equation (SI & US), Chezy Equation, Froude Number, Hydraulic
Radius, Hydraulic Jump, Critical Depth, Specific Energy, Reynolds Number, and
more

Pipe Flow — 7 Calculators
- Darcy-Weisbach Equation, Hazen-Williams Velocity (SI & US), Reynolds Number,
Water Hammer Pressure, Continuity Equation, Minor Head Loss

Stormwater & Watershed — 9 Calculators
- SCS Curve Number Runoff, SCS Peak Discharge, IDF Rainfall Intensity, Kirpich
Time of Concentration, Gumbel Extreme Value, Detention Storage Volume,
Composite Curve Number, and more

Pumps & Water Supply — 7 Calculators
- Total Dynamic Head, Water Horsepower, Brake Horsepower, NPSHa, Affinity Laws
for Flow, Head, and Power

Weirs & Orifices — 6 Calculators
- Rectangular Weir (SI & US), V-Notch Weir, Broad-Crested Weir, Orifice Flow,
Spillway Discharge

Water Flow — 10 Calculators
- Water Flow Rate, Velocity of Water, Volume of Water Flow, 90° V-Notch
calculations, Pipe Total Diameter, and more

Surface Runoff — 6 Calculators
- Average Velocity, Runoff, Travel Time, Hourly Rate of Rainfall

Groundwater — 7 Calculators
- Darcy's Law, Thiem Equation, Cooper-Jacob Drawdown, Dupuit Well Flow, Radius
of Influence, Storage Properties

Soil Pollution — 5 Calculators
- Groundwater Pore Velocity, Effective Diffusion, Hydrodynamic Dispersion,
Aquifer Parameter, Variance of Pore Velocity

River Pollution — 7 Calculators
- River Oxygen Deficit, Critical Time & Distance for Oxygen Deficit,
Re-Aeration Constants, Dissolved Oxygen, River Flow, Water Temperature

Lake Pollution — 4 Calculators
- Waste Entering, Equilibrium Concentration, Settling Loss Rate, Particle
Deposition Rate

Sediment Transport — 4 Calculators
- Shields Parameter, Bed Shear Stress, Stokes' Law Settling Velocity,
Meyer-Peter Müller Bedload

Snow Hydrology — 2 Calculators
- Snow Water Equivalent, Degree-Day Snowmelt

Culvert Hydraulics — 2 Calculators
- Culvert Headwater (Outlet Control), Culvert Outlet Control Head Loss

Flood Routing
- Muskingum Routing

Water Balance
- Water Balance Equation, Storage Continuity

Plus: Area Formulas, Pollution Cleanup, and more

CONVERSIONS & REFERENCE

Hundreds of built-in conversions across 16 categories including:
- Liquid Measures, Cubic Measures, Linear Measures, Square Measures
- Flow Rates, Pressures, Horsepower, BTU, Watts, Power
- Hydraulic Conversions, Sand-to-Volume, Ft-Lbs
- 8 Temperature Scales (Celsius, Fahrenheit, Kelvin, Rankine, Réaumur, Newton,
Delisle, Rømer)
- Metric Conversions and Fraction Conversions

KEY FEATURES
- Save and review past calculations
- Switch between US (Imperial) and Metric units
- Clean, intuitive interface designed for field and office use
- Premium upgrade unlocks Groundwater, Pollution, Sediment Transport, Snow
Hydrology, Culvert Hydraulics, and Flood Routing calculators