Heat Energy (Q = mcΔT) Calculator

Work out heat energy (q = mcδt) instantly with clear inputs, formula shown and shareable results.

About Heat Energy (Q = mcΔT) Calculator

Q = mcdT is the workhorse of calorimetry: heating 5 kg of water by 40 K takes 837 kJ, which a 2 kW immersion heater delivers in about 419 seconds. The relation assumes no phase change - crossing a melting or boiling point needs latent heat added separately.

Formulas

Sensible heat

Q = m x c x dT

Heating time

t = Q / power

Worked example

With the default values below, Heat Energy (Q = mcΔT) Calculator returns Heat Energy of 837,200.0. Change any input above and every figure here is recalculated in your browser.

Inputs used

Massminimum 0 kg: 5 kg
Specific heat capacityminimum 0 J/(kg K): 4,186 J/(kg K)
Temperature change: 40 K

Results

Heat Energy: 837,200.0 J
Same Energy In Kilojoules: 837.2000
Same Energy In Watt-Hours: 232.5556
Time A 2 kW Heater Would Take: 418.600 s

Step by step

1Values used
2Sensible heat
3Heating time
4Heat Energy= 837,200.0 J
5Same Energy In Kilojoules= 837.2000
6Same Energy In Watt-Hours= 232.5556
7Time A 2 kW Heater Would Take= 418.600 s

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why does my kettle take longer than this predicts?

Heat leaks to the surroundings and warms the kettle body itself, so real efficiency is typically 80-90%.

What if the water boils?

Then latent heat takes over at constant temperature - about 2260 kJ per kilogram, far more than raising it to boiling point.