Specific heat calculator (Q = mcΔT)
Enter the mass, specific heat and the start and end temperatures to get the energy in joules, kilowatt hours and kilocalories.
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How to use it
- Enter mass, specific heat (water about 4184), initial temperature and final temperature.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Q = m × c × (T₂ − T₁); a negative result means heat released. 1 kWh = 3,600,000 J and 1 kcal = 4184 J.
Example
Inputs: Mass = 1 kg, Specific heat (water about 4184) = 4,184 J/(kg·K), Initial temperature = 20 °C, Final temperature = 100 °C. Result: Heat energy: 334,720 J; In kilojoules: 334.72 kJ; In kilowatt hours: 0.09298 kWh.
Limits and caveats
- It assumes a constant specific heat over the range and no phase change such as melting or boiling.
- Water's specific heat varies slightly with temperature; 4184 is an approximation near room temperature.
Questions about this tool
What are some specific heat values?
Roughly: water 4184, aluminum 900, iron 450 and copper 385 J/(kg·K).
Why no conversion from °C to K?
A temperature difference is the same in both scales, so a 1 °C change equals a 1 K change.
How much energy heats 1 liter of water from 20 to 100 °C?
About 335 kJ, roughly 0.093 kWh before losses.