Result preview
Submit the form to see equilibrium temperature, body heat transfer, balance checks, export options, and the graph above the calculator.
Heat balance calculator form
Use up to three bodies, then include external heating and thermal losses.
Example data table
| Body | Material | Mass (kg) | Specific Heat (kJ/kg°C) | Initial Temp (°C) |
|---|---|---|---|---|
| Body 1 | Water | 2.000 | 4.186 | 80.000 |
| Body 2 | Aluminum | 1.500 | 0.897 | 25.000 |
| Body 3 | Copper | 1.000 | 0.385 | 20.000 |
| External heat input: 40 kJ | Heat loss: 10 kJ | Approximate final equilibrium: 73.359 °C | ||||
Formula used
The calculator assumes a lumped, well-mixed system. Each active body stores sensible heat only. External heating adds energy, while losses remove energy.
Units used here are kilograms, kilojoules, and degrees Celsius, so the balance remains consistent throughout the page.
How to use this calculator
- Enter names for up to three bodies. You can leave one body inactive by setting mass to zero.
- Choose a material preset or enter a custom specific heat.
- Provide mass and initial temperature for each active body.
- Add any external heat input from a heater or controlled source.
- Enter expected heat loss to the environment.
- Press Calculate Heat Balance to see the equilibrium temperature and body heat transfer above the form.
- Use the CSV button to export numeric results.
- Use the PDF button to save the result section for reporting, review, or coursework.
Frequently asked questions
1) What does this calculator actually solve?
It solves the final equilibrium temperature of multiple bodies after energy exchange. It also reports each body’s heat gain or release, total capacity, net external energy, and closure error.
2) Which unit system should I use?
Use kilograms for mass, kilojoules for external energy, and kilojoules per kilogram per degree Celsius for specific heat. Keep all entries in the same unit system.
3) Can I model only two bodies?
Yes. Enter valid values for two bodies and set the third body mass to zero. The calculator automatically ignores inactive entries with zero mass or zero heat capacity.
4) Why does one body show negative heat transfer?
A negative value means that body releases heat to the rest of the system. A positive value means it absorbs heat as the mixture approaches the common final temperature.
5) What is energy closure error?
It is the difference between summed body heat transfer and net external energy. Ideally it should be extremely close to zero, with only tiny rounding differences remaining.
6) Does this include phase change?
No. This page models sensible heating and cooling only. Melting, freezing, boiling, and condensation require latent heat terms and separate balance stages.
7) When should I use a custom specific heat?
Use a custom value when your material is not listed, when temperature-dependent data is known, or when a measured laboratory value is more appropriate than a preset.
8) Is the final temperature always between the starting temperatures?
Not always. With external heating or strong losses, the final equilibrium can move above or below the initial weighted average, depending on the net energy added or removed.