Specific Heat and Heat Energy Calculator
How much energy does it take to change a temperature?
Your numbers
Your results
Heat energy (kJ)
Heat energy (kJ)
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Energy (kWh)
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Energy (kcal)
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Heating time at 2 kW (minutes)
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Specific Heat and Heat Energy Calculator by TheCalcTools
How the Specific Heat and Heat Energy Calculator works
Enter the mass, choose the material and enter the start and end temperatures.
The energy is mass times specific heat times the temperature change.
A negative result means heat is released as the material cools.
The formula
Q = m × c × ΔT
Worked example
Using the default values shown in the calculator:
| Mass (kg) | 2 |
|---|---|
| Material | Water (4186 J/kg·K) |
| Initial temperature (°C) | 20 |
| Final temperature (°C) | 100 |
- ΔT = 100 − 20 = 80 °C.
- Q = 2 × 4,186 × 80 = 669.8 kJ.
- That is 0.186 kWh, about 5.6 minutes on a 2 kW heater.
Result:
| Heat energy (kJ) | 669.76 |
|---|---|
| Energy (kWh) | 0.1860 |
| Energy (kcal) | 160.08 |
| Heating time at 2 kW (minutes) | 5.6 |
Frequently asked questions
Why does water heat so slowly?
Water has a very high specific heat for a common substance. It takes 4,186 J to warm one kilogram by one degree.
Does this include phase changes?
No. Melting or boiling needs extra latent heat that is not included here.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.