Calculate how much heat energy is needed to change the temperature of a substance, based on mass, specific heat capacity and temperature change.
The heat energy (Q) needed to change the temperature of a substance equals the mass (m) multiplied by the specific heat capacity (c) and the temperature change (ΔT). Heat energy is measured in joules (J).
Specific heat capacity is a material property that tells you how much energy is needed to raise the temperature of 1 kg of the substance by 1 °C. Some common values: water ≈ 4186 J/(kg·°C), ice ≈ 2100 J/(kg·°C), air ≈ 1005 J/(kg·°C), iron ≈ 450 J/(kg·°C). Swap the default value in the calculator for the correct figure for the material you're working with.
Specific heat capacity is how much energy is needed to raise the temperature of 1 kg of a substance by 1 °C. It varies from substance to substance and is measured in joules per kilogram per degree Celsius (J/(kg·°C)).
Water molecules form strong hydrogen bonds that take a lot of energy to break or set in motion, giving water an unusually high heat capacity. Metals, on the other hand, have simpler atomic structures that heat up faster with less energy, giving them lower heat capacity.
Enter the mass of the water in kilograms, leave the heat capacity at the default value of 4186 J/(kg·°C), and enter how many degrees you want to raise the temperature. The calculator then shows how many joules (and kilojoules) are needed.