What this calculator does
The heat capacity formula, Q = m·c·ΔT, works out how much heat energy is needed to change the temperature of a mass by a given amount. The term that makes materials behave so differently is c, the specific heat capacity: the energy needed to raise one kilogram of that particular substance by one degree Celsius. Water needs far more energy per kilogram than metals do, which is why a metal pan heats almost instantly while the water in it takes minutes.
This calculator works for any material, not just water, by letting the specific heat capacity be set from a short list of common substances or entered directly as a custom value. That makes it useful for comparing how differently metals, glass, ice and other materials respond to the same amount of heating, using the same underlying heat capacity formula throughout.
The formula
Multiply mass by specific heat capacity by the temperature change (target minus starting temperature) to get the heat energy Q, in joules. A negative result means the material is being cooled rather than heated; the calculator reports the size of that energy transfer either way and shows the direction alongside it.
| Term | Meaning |
|---|---|
| Q | Heat energy transferred, in joules (or the kilojoule, kilocalorie and kilowatt-hour equivalents shown alongside it). |
| m | Mass of the material being heated or cooled. |
| c | Specific heat capacity of the material: the energy needed to raise one kilogram of it by one degree Celsius. |
| ΔT | Temperature change, target temperature minus starting temperature. |
The inputs explained
| Field | What to enter |
|---|---|
| Material | Choose a common material to use its typical specific heat capacity, or select custom to enter your own. |
| Specific heat capacity (custom material only) (J/(kg·°C)) | Only used when material is set to custom. Enter the specific heat capacity in joules per kilogram per degree Celsius. |
| Mass (kg) | The mass of the material being heated or cooled. |
| Starting temperature (°C) | The temperature the material starts at. |
| Target temperature (°C) | The temperature the material is being heated or cooled to. |
When to use it
Comparing how fast different materials heat up
The same mass and temperature change needs very different amounts of energy depending on the material: water needs roughly nine times as much energy per kilogram as copper for the same temperature rise, which is why metal handles warm up quickly while water in the same pot lags behind.
Estimating energy use for an industrial or workshop heating process
Working out the heat energy required for a batch of material, such as metal stock or glass, before a furnace or kiln cycle gives a starting estimate for the energy input needed, before accounting for losses.
Checking a physics or engineering problem by hand
Where a textbook problem gives a specific heat capacity value that is not water, entering it as a custom value confirms the arithmetic on Q = mcΔT independently.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
Heat energy needed to warm 2 kg from 20°C to 100°C, by material
The same mass and temperature change, applied to a range of materials.
| Material | Heat energy required |
|---|---|
| Water | 669.76 kJ |
| Ice | 336.00 kJ |
| Aluminium | 144.00 kJ |
| Iron | 72.00 kJ |
| Copper | 61.60 kJ |
| Glass | 134.40 kJ |
Heat energy needed to warm water from 20°C to 100°C, by mass
A fixed temperature rise for water, across a range of masses.
| Mass of water | Heat energy required |
|---|---|
| 0.5 kg | 167.44 kJ |
| 1 kg | 334.88 kJ |
| 2 kg | 669.76 kJ |
| 5 kg | 1,674.40 kJ |
| 10 kg | 3,348.80 kJ |
Questions
How is this different from the heat capacity of water calculator?
The heat capacity of water calculator is fixed to water's specific heat capacity and also estimates heating time from a heater power rating. This calculator instead works for any material, with an editable specific heat capacity, so it applies to metals, glass, ice or a custom substance.
What is specific heat capacity, in plain terms?
It is the energy needed to raise one kilogram of a substance by one degree Celsius. A high specific heat capacity, like water's, means the material resists temperature change; a low one, like most metals, means it heats and cools quickly for the same energy input.
Does this formula apply during a phase change, such as melting or boiling?
No. Q = mcΔT only applies while the material stays in one phase (solid, liquid or gas). Melting or boiling absorbs or releases additional energy, called latent heat, at a constant temperature, which this formula does not account for.
Where do the specific heat capacity values in the material list come from?
They are standard reference values for each material near room temperature: for example, water at 4,186 J/(kg·°C) and aluminium at about 900 J/(kg·°C). Real specific heat capacity varies slightly with temperature and purity, so the custom option is there for a more precise or unusual figure.
For a version of this formula fixed to water, with an added heating-time estimate from heater power, see the heat capacity of water calculator. For phase-change energy such as melting or boiling, see the evaporation rate calculator.