Specific Heat Calculator
Calculate the heat needed to warm or cool a material with Q = m × c × ΔT, or solve for the mass, the specific heat capacity or the final temperature. Pick water, aluminium, copper, iron and other materials, and add a heater power to see how long it takes.
Negative = heat removed (cooling)
Estimates the heating time with no heat losses
How to use the Specific Heat Calculator
- Choose what to solve for: heat energy, mass, specific heat or final temperature.
- Pick a material or choose Custom and type its specific heat.
- Enter the mass and the start and end temperatures (or the heat, when solving for the temperature).
- Optionally enter a heater power in watts to estimate the heating time.
- Read the result in several energy units and compare materials in the table.
The specific heat formula
Q = m × c × ΔT
Q is the heat energy (J), m the mass (kg), c the specific heat capacity (J/(kg·°C)) and ΔT = Tfinal − Tinitial. Rearranged: c = Q ÷ (m ΔT), m = Q ÷ (c ΔT), ΔT = Q ÷ (m c). With a heater of power P (watts), the ideal heating time is t = Q ÷ P.
Example: warming a 500 g aluminium pan from 20 °C to 200 °C takes Q = 0.5 × 897 × 180 = 80,730 J ≈ 80.7 kJ.
Specific heat capacities of common materials
| Material | J/(kg·°C) | cal/(g·°C) |
|---|---|---|
| Water (liquid, 25 °C) | 4,184 | 1.000 |
| Ethanol | 2,440 | 0.583 |
| Steam (100 °C, constant pressure) | ~2,080 | ~0.50 |
| Ice (−10 °C) | ~2,050 | ~0.49 |
| Wood (varies by species) | ~1,200–2,300 | ~0.3–0.55 |
| Air (constant pressure, 25 °C) | 1,005 | 0.240 |
| Aluminium | 897 | 0.214 |
| Concrete | ~880 | ~0.21 |
| Glass | ~840 | ~0.20 |
| Iron | 449 | 0.107 |
| Copper | 385 | 0.092 |
| Silver | 235 | 0.056 |
| Gold | 129 | 0.031 |
| Lead | 129 | 0.031 |
Values are typical at room temperature and atmospheric pressure. Specific heat changes somewhat with temperature, and mixtures such as concrete, glass and wood vary with composition.
Phase changes
Q = mcΔT only applies while the material stays in one phase. Melting or boiling absorbs latent heat at a constant temperature: Q = m L, with L ≈ 334 kJ/kg for melting ice and ≈ 2,257 kJ/kg for boiling water at 100 °C. To turn ice at −10 °C into steam, add the heating stages and the two latent-heat stages together.
Frequently asked questions
What is the formula for specific heat?
The heat Q needed to change the temperature of a mass m by ΔT is Q = m × c × ΔT, where c is the specific heat capacity. Rearranged: c = Q ÷ (m ΔT), m = Q ÷ (c ΔT) and ΔT = Q ÷ (m c). A positive Q means heat is absorbed; a negative Q means heat is released as the material cools.
What is the specific heat of water?
About 4,184 J/(kg·°C), which is 1 cal/(g·°C) or 1 BTU/(lb·°F). Water's specific heat is unusually high, which is why it is used for heating and cooling systems and why oceans moderate the climate. It varies slightly with temperature (about 4,180 to 4,220 J/(kg·K) between 0 and 100 °C).
How much energy does it take to heat water?
Heating 1 litre (1 kg) of water from 20 °C to 100 °C needs Q = 1 × 4,184 × 80 = 334,720 J, about 335 kJ or 0.093 kWh. A 2,000 W kettle would take about 167 seconds if no heat were lost; real kettles take a little longer.
Is a change of 1 °C the same as 1 K?
Yes. Temperature differences are the same size in Celsius and kelvin, so J/(kg·°C) and J/(kg·K) are identical. A change of 1 °F is 5/9 of a kelvin; the calculator converts automatically.
Does Q = mcΔT work through melting or boiling?
No. During a phase change the temperature stays constant while latent heat is absorbed: Q = m × L. For water, melting takes about 334 kJ/kg and boiling about 2,257 kJ/kg. Calculate each heating stage and each phase change separately and add them up.
What is the difference between specific heat and heat capacity?
Specific heat c is per unit mass (J/(kg·K)). Heat capacity C = m × c is for a whole object (J/K): the energy needed to warm that object by one degree. The calculator shows both.
Why do metals heat up faster than water?
Metals have low specific heats. Copper's is about 385 J/(kg·K), roughly a tenth of water's, so the same energy warms a kilogram of copper about ten times more than a kilogram of water.