Heat Energy Calculator

1. Enter any two of energy, mass and temperature change.
2. Leave the one you want to find blank.
3. Set the specific heat for your substance (it defaults to 4186 for water).
4. Read the result and the formula used.

Here is what each result means:

Heat energy is the energy you must add to or remove from a substance to change its temperature. How much you need depends on three things: the mass of the substance, how big a temperature change you want, and a property called the specific heat. Put together, they give the rule energy equals mass times specific heat times the change in temperature.

The specific heat is the energy needed to raise one kilogram of a substance by one degree. Water has a high specific heat of about 4186 joules per kilogram per degree, which is why it takes so long to boil and why the sea warms and cools slowly. Metals have much lower values, so they heat up and cool down quickly. In SI units heat energy is measured in joules.

Because the same formula works for both heating and cooling, a negative temperature change simply means energy is being removed. The relationship assumes the substance does not change state: melting, boiling or freezing need extra energy that this formula does not include. Within a single state, though, it accurately predicts the energy for any temperature change.

It rearranges one relation to solve for whichever value you leave blank.

1. For energy, multiply mass by specific heat by the temperature change.
2. For mass, divide energy by specific heat times the temperature change.
3. For temperature change, divide energy by mass times specific heat.

Heat is one form of energy; see the kinetic energy calculator and potential energy calculator.

Heat 2 kilograms of water by 10 degrees, with a specific heat of 4186.

Calculation: Q = m c dT = 2 x 4186 x 10 = 83720 joules. To find the temperature rise from 209,300 joules for 5 kilograms of water, divide: 209,300 over 5 times 4186 is 10 degrees.

One relation, rearranged for whatever you need to find.

All three come from Q equals m c times the temperature change, so any two of energy, mass and temperature change give the third once the specific heat is set. The specific heat acts as a fixed property of the substance, linking the amount of matter to the energy each degree of change requires.

The specific heat varies widely, which is why substances heat up at very different rates.

Water stands out with by far the highest specific heat of common materials, storing a great deal of energy for each degree. Metals sit at the low end, which is why a metal spoon in hot water heats up almost at once while the water itself takes much longer.

The Mass

More mass needs more energy for the same temperature change, in direct proportion.

The Temperature Change

A bigger change needs more energy. Doubling the temperature rise doubles the energy.

The Specific Heat

A substance with a higher specific heat needs more energy per degree. Water needs far more than most metals.

Physics and Chemistry Homework

Solve for energy, mass or temperature change in a calorimetry problem.

Engineering and Heating

Estimate the energy to heat water in a tank, boiler or radiator.

Cooking and Science

Work out how much energy a temperature change requires for a given amount of a substance.

1. Using the Wrong Specific Heat

Each substance has its own value. Using water's 4186 for a metal overstates the energy by nearly ten times.

2. Forgetting It Is a Change

Use the temperature change, not the final temperature. A rise from 20 to 30 degrees is a change of 10.

3. Ignoring Changes of State

Melting or boiling needs extra latent heat that this formula does not include.

4. Mixing Units

Use kilograms and joules with a specific heat in joules per kilogram per degree.

5. Zero Mass or Temperature Change

Solving for mass or temperature change cannot divide by zero.

The relation is exact; only the displayed decimals are rounded, and very large results are shown in scientific notation.

Heat energy is the energy needed to change a substance's temperature. It equals mass times specific heat times the temperature change. Heating 2 kilograms of water by 10 degrees needs about 83,720 joules.

Multiply the mass by the specific heat by the temperature change. For 2 kilograms of water raised 10 degrees, that is 2 times 4186 times 10, which is 83,720 joules.

Specific heat is the energy needed to raise one kilogram of a substance by one degree. Water's is about 4186 joules per kilogram per degree, much higher than most metals.

Divide the energy by mass times specific heat. Leave the temperature change field blank and enter energy and mass, and the calculator solves for it.

Yes. The same formula applies to cooling. A negative temperature change means energy is being removed rather than added.

Use 4186 for water. Common values are about 900 for aluminium, 450 for iron and 385 for copper. Change the specific heat field to match your substance.

No. Changing state needs extra latent heat that this formula does not cover. It only applies while the substance stays in one state.

Joules for energy, kilograms for mass, degrees for temperature change and joules per kilogram per degree for specific heat. Keep the units consistent for a correct result.

No. The calculation runs in your browser and nothing you enter is stored or sent anywhere, unless you choose Save, which keeps the result only on this device.

• Specific heat capacity (Wikipedia).
• Heat (Wikipedia).
• Specific heat explained (Maths Is Fun).