Heat Energy Calculator

Heat energy depends on the mass, the specific heat capacity of the material and the temperature change. Pick a common material or enter your own specific heat.

Results update as you type.

Heat energy

627.9 kJ

Electricity to supply it
0.17442 units (kWh)at 100% efficiency
In J
6,27,900 J
In MJ
0.6279 MJ
In cal
1,50,071.7 cal
In kcal
150.0717 kcal
In Wh
174.41667 Wh
In kWh
0.17441667 kWh

A negative result means heat is given out (cooling). Melting or boiling needs extra latent heat that this formula does not include.

About this calculator

It also shows the electricity, in units, needed to supply that heat.

How to use it

  1. Choose what to find, enter the other values with their units, and read the answer in every common unit.

The formula

Q = m × c × ΔT
m
mass
c
specific heat capacity
ΔT
temperature change

Worked example

Heating 2 kg of water from 25 °C to 100 °C

  1. Q = 2 × 4,186 × 75 = 6,27,900 J = 628 kJ.
  2. That is 0.17 units of electricity at 100% efficiency.

What the result means

Water has a very high specific heat, which is why it is used in radiators and why the sea warms slowly.

Assumptions

  • No change of state.

Limitations

  • Boiling or melting need latent heat as well.

Frequently asked questions

What is specific heat capacity?

The energy to warm 1 kg of a material by 1 °C.

What is the specific heat of water?

About 4,186 J/(kg·K), or 1 cal/(g·°C).

Is ΔT the same in °C and K?

Yes, a change of 1 °C equals a change of 1 K.

Last reviewed on 6 October 2026. Found a mistake? Tell us.