WaterCalculator

Water Science Calculators

29 tools for the physical and chemical side of water — density, weight, heat, phase changes, viscosity, humidity, and more. Each runs on the recognised standard formula, with the working and sources shown.

John Mac, PE Curated and reviewed by John Mac, PE, Water Systems Specialist.

Weight, density & mass

Water Weight CalculatorWeight of water by volume and temperature. Water Density CalculatorDensity of water from temperature and salinity. Density by TemperatureHow water's density changes across 0–100 °C. Specific Gravity CalculatorA fluid's density relative to pure water. Molar Mass of WaterThe molar mass of H₂O, 18.015 g/mol. Moles of WaterMoles of water from a mass or volume.

Heat & energy

Specific Heat of WaterEnergy, mass and temperature change for water. Energy to Heat WaterEnergy needed to raise water's temperature. Energy to Boil WaterEnergy to bring water up to boiling. Heat of VaporizationEnergy to turn water into steam. Ice Melting EnergyEnergy to melt ice into liquid water.

Temperature & phase change

Boiling Point at AltitudeHow boiling point falls as altitude rises. Freezing ExpansionHow much water expands when it freezes. Thermal ExpansionVolume change as water warms or cools.

Fluid & physical properties

Buoyancy CalculatorBuoyant force on an object in water. Water DisplacementVolume or weight of water an object displaces. Surface TensionWater's surface tension and capillary rise. Viscosity of WaterDynamic and kinematic viscosity by temperature.

Humidity & vapour

Water Vapour PressureSaturation vapour pressure of water. Dew Point CalculatorDew point from temperature and humidity. Humidity to Water ContentAbsolute humidity from relative humidity. Condensation RateWater condensing out of humid air.

Chemistry & quality

Water ElectrolysisHydrogen and oxygen from splitting water. Dissolved OxygenDissolved-oxygen saturation by temperature. Water Quality IndexAn overall quality score from key parameters.

Hydrology & power

Streamflow CalculatorStream discharge from area and velocity. Watershed RunoffRunoff from rainfall and catchment area. Hydroelectric PowerPower output from flow and head. Micro-Hydro PowerOutput for small-scale hydro systems.

About our science calculators

These tools model pure water at atmospheric pressure unless you tell them otherwise, using standards such as the Kell equation for density and the IAPWS formulations for viscosity and surface tension. Every figure is verified against the live calculator, and each page lists its sources. For the full detail of how we build and check them, see our methodology.

Browse other categories

FlowPipe flow, velocity, friction loss. PressureHead, PSI, depth and losses. UsageHousehold use, footprints, savings. CostBills, rates and running costs. TreatmentSoftening, filtration, chemistry. PumpsSizing, head, horsepower, NPSH. DrainageSlopes, drain sizing, stormwater.