Specific Heat Calculator
Q = mcΔT: heat energy, mass, specific heat or temperature change.
About this tool
Choose what to solve for and a material (or type a specific heat), then enter the mass and temperatures or the energy. The result shows energy in kJ, kWh, kcal and BTU and how long a heater of a given wattage would take.
Heat, mass and temperature
The energy needed to change a material's temperature is Q = m × c × ΔT: mass times specific heat capacity times the temperature change. Specific heat varies widely. Water's is very high at 4,186 J/kg·K, which is why it's used in radiators and hot-water bottles and why oceans moderate climate. Metals are low: copper is 385 J/kg·K, so the same energy heats it about eleven times as much. Heating 1 kg of water from 20 °C to 100 °C takes about 335 kJ (0.093 kWh, or 80 kcal), roughly 2.8 minutes in a 2 kW kettle if no heat were lost. Rearranged, the same equation finds a mass, an unknown specific heat from an experiment, or the final temperature after adding a known amount of energy. Honest limits: specific heat changes slightly with temperature; real heating loses energy to containers and the air, so allow for efficiency; and melting or boiling need extra latent heat (334 kJ/kg to melt ice, 2,257 kJ/kg to boil water), which the tool warns about when your range crosses those points. The energy calculator and the thermal expansion calculator are related.
Frequently asked questions
What is the formula for specific heat?
Q = m × c × ΔT, so c = Q ÷ (m × ΔT).
What is the specific heat of water?
About 4,186 J/kg·K (4.186 J/g·°C, or 1 cal/g·°C).
How much energy does it take to boil 1 litre of water?
About 335 kJ to heat it from 20 °C to 100 °C, plus 2,257 kJ more to turn it all to steam.
Why does water have a high specific heat?
Hydrogen bonds between molecules absorb a lot of energy before the temperature rises.
Is my data sent anywhere?
No. Everything is calculated in your browser, and nothing is stored or sent.