Enter the mass of the water and the total change in temperature into the calculator to determine the energy to heat water.

Energy to Heat Water Formula

The following formula is used to calculate the energy required to heat a body of water. 

E = m * C * ΔT
  • Where E is the total energy required (J)
  • m is the mass of the water (g)
  • C is the specific heat (J/g/C)
  • ΔT is the change in temperature (C)

How much energy is required to heat water?

The energy required to heat water if determined by three factors.

First, the total mass of the water. The greater the mass of water, the more energy it will take to heat it.

Next, the specific heat of the water. This value is most a constant. While the specific heat does vary with temperature, the small change is often negligible and ignored.

Lastly, the amount of temperature change. The greater the change in temperature the greater the energy.

Example Problem

How to calculate energy to heat water?

First, determine the total mass of the water and the change in temperature. For this example, the mass of the water is 400 grams and the temperature change is 20 C.

Next, we will use the specific heat of fresh water at room temperature which happens to be 4.18 J/g/C.

Finally, calculate the energy required to heat the water using the formula above:

E = m * C * ΔT

E = 400 * 4.18 * 40

E = 66, 880 Joules