Use q = mcΔT to find the heat energy needed to warm something up, or solve for mass, specific heat capacity or temperature change. Pick a material for its c value, and switch between J, kJ, calories and kWh.
Specific heat formula
Worked example
How much energy heats 1 kg of water from 25 °C to 100 °C? ΔT = 75 °C, so q = 1 × 4184 × 75 = 313,800 J (314 kJ, or 0.087 kWh). This does not include the much larger energy to boil it (latent heat of vaporisation, 2,260 kJ/kg).
Specific heat capacities
| Substance | J/(g·°C) | Substance | J/(g·°C) |
|---|---|---|---|
| Water (liquid) | 4.184 | Aluminium | 0.897 |
| Ice | 2.09 | Iron | 0.449 |
| Steam | 2.01 | Copper | 0.385 |
| Ethanol | 2.44 | Lead | 0.129 |
Water’s unusually high specific heat is why oceans moderate climate and why it is used in radiators and hot-water bottles.
Frequently asked questions
What is specific heat capacity?
The energy needed to raise the temperature of 1 kg (or 1 g) of a substance by 1 °C. Water’s is 4,184 J/kg·°C, one of the highest of common substances.
How do I calculate heat energy?
Multiply mass × specific heat × temperature change: q = mcΔT. Leave the q box empty and enter the other three.
Is ΔT in Celsius or Kelvin?
Either. A change of 1 °C is exactly a change of 1 K, so ΔT has the same value in both.
Does it include phase changes?
No. q = mcΔT applies within one phase. Melting or boiling needs latent heat: q = m × L, added separately.
Related tools
Free educational tool by HawkInc. Results are calculated in your browser and rounded for display; check critical work by hand or with a second method.