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Calculate water density instantly by entering temperature and salinity. Get accurate results in kg/m³ or g/cm³.
Water reaches its maximum density (approximately 1 g/cm³) at around 4°C.
Enter a volume to automatically calculate the mass of water based on its current density.
The Kell equation is used to calculate pure water density variation with temperature at 1 standard atmosphere. Actual density can also be influenced by dissolved impurities, salinity, and pressure. Results are approximate estimations for pure water.
Overview
Understand what the tool solves, how it works, and the boundaries of its data.
Enter a temperature in degrees Celsius to see an estimated density for pure liquid water. The result is shown in g/cm³, kg/m³, and lb/ft³. If you also enter a volume in liters, the page multiplies that volume by the calculated density and reports an estimated mass in grams or kilograms. The default temperature is 4°C; changing either input recalculates the result.
Density means mass per unit volume. It varies with temperature, so a liter of water does not correspond to exactly the same mass at every temperature. The conversion between the displayed metric units is direct: 1 g/cm³ equals 1,000 kg/m³. NIST publishes equations for water density and distinguishes conditions and formulations; IAPWS also describes how the appropriate formulation depends on whether the use is general thermodynamic work or metrology.
Guide
Follow the workflow and verify inputs and outputs with practical examples.
Enter the water temperature in °C. The formula accepts numeric input; the page starts at 4°C.
Optionally enter a positive volume in liters. Leave it blank if you only need density.
Read the recalculated density in the available units. When a volume is present, also read the corresponding estimated mass.
Use Reset to return the temperature to 4°C and clear the volume.
Example: at 20°C and 1.5 L, the calculator gives approximately 998.204 kg/m³ and an estimated mass of 1,497.3 g (about 1.4973 kg). This is a calculation from the entered volume and the page’s density estimate, not a measurement of a sample.
Use cases
See how the tool fits into real work and everyday tasks.
Use several temperatures to see how the density estimate changes and understand why one fixed value is only an approximation.
Enter liters to estimate the mass of pure water for a classroom calculation or rough planning note.
Read the same estimate in metric or US customary density units when comparing notes that use different unit conventions.
Q&A
Find concise answers to common questions and confusing cases.
That value is a convenient approximation. Water density changes with temperature, and the displayed estimate reflects the temperature you enter.
Multiply g/cm³ by 1,000 to get kg/m³. For example, 0.9982 g/cm³ is 998.2 kg/m³.
The calculation multiplies the estimated density by the entered volume, with unit conversion to grams. It is a derived estimate, not an additional measurement.
The calculator has no salinity or pressure input. Its output should not be treated as a saltwater, pressure-corrected, or metrology-grade result.
Notes
Review scope, result limitations, and important precautions before use.
The calculation is intended as an estimate for pure liquid water near one atmosphere over 0–100°C. The page still evaluates numeric temperatures outside that interval, but those results are outside the intended range. It does not account for salinity, dissolved substances, pressure changes, ice, or steam. For laboratory calibration, engineering design, or a measured water sample, use a formulation and data source suited to the sample and required uncertainty; the calculator output is not a sample measurement.
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