How this calculator works
The heating path uses approximate constant heat capacities for ice, liquid water and steam, plus latent heat at 0 C and 100 C. Crossing a boundary adds the full phase-change energy. An endpoint at 0 C means liquid water after melting; an endpoint at 100 C means liquid water before boiling. Volume uses a liquid-water equivalent density of 1000 kg/m³. Efficiency accounts for the fraction of heater input reaching the water. Inverse state modes use delivered energy and report a phase fraction if melting or boiling is incomplete.
Formula
Q = sum(m c_phase deltaT_phase) + m L_fusion + m L_vaporization for crossed transitions; t = Q/(efficiency times P). Values: c_ice = 2090, c_water = 4186, c_steam = 2020 J/(kg K); Lf = 334000, Lv = 2256000 J/kg.
Worked example
Heating 1 kg of liquid water from 20 C to 30 C needs 41860 J, or 41.86 s at 1 kW and 100% efficiency. Heating 2 kg from -10 C to 10 C needs 793520 J including melting.
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Frequently asked questions
Can I calculate boiling at altitude?
This model fixes phase changes at 0 C and 100 C, approximately atmospheric pressure. Different pressures need different transition temperatures and properties.
Does this include the kettle or tank?
No. Its thermal mass and other losses need to be included separately or reflected in a suitable effective efficiency.
Can I enter the actual volume of ice or steam?
Use mass, or the equivalent liquid volume. The volume option assumes 1000 kg/m³ and does not use ice or steam density.