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