💧 Water Density Calculator
Water Density Calculator
Inputs
Results
Density- lb/ft³
Specific Weight- lbf/ft³
Dynamic Viscosity- Pa·s
Calculator Description
Water density varies with temperature, reaching its maximum (approximately 1000 kg/m³) at 4°C. This calculator computes water density from temperature using a polynomial approximation formula.
What this calculator finds
It calculates water density at a given temperature (0–100°C range) in kg/m³ or g/cm³. Both liquid water (default) and steam are supported.
Why it matters
- Density directly affects Reynolds number, flow rate, pressure drop, and other fluid dynamics calculations
- Buoyancy force in natural convection is determined by density differences in heat transfer calculations
- Accurate water density is needed for adjusting reactant concentration and flow rates in chemical processes
Formula
Polynomial Approximation for Water Density
A simplified version of Kell's polynomial is used, providing accuracy within ±0.05% over the 0–100°C range.
- ρ(T) — Water density at temperature T [kg/m³]
- T — Temperature in Celsius [°C] (0–100°C)
Reference density values
- 0°C: 999.8 kg/m³
- 4°C: 1000.0 kg/m³ (maximum density)
- 20°C: 998.2 kg/m³
- 100°C: 958.4 kg/m³
Useful Tips
Practical tips
- For general process calculations, 998.2 kg/m³ at 20°C is commonly used as an approximation
- Density change is minimal near 4°C, so temperature effects are small in chilled water systems
- Seawater density differs from fresh water at approximately 1025 kg/m³ due to salinity (~3.5%)
Limitations & cautions
- This formula is for pure (distilled) water and does not account for density changes from dissolved salts or gases
- At high pressures (>10 bar), pressure-induced density changes must be considered separately
- Freezing causes ~9% volume expansion, requiring caution in freeze protection design