Specific heat formula
The heat energy transferred is Q = m·c·ΔT, where m is mass, c is the specific heat capacity, and ΔT is the temperature change. A positive Q means heat absorbed. To gauge measurement accuracy of c, see the percent error calculator.
Each factor pulls its weight independently: doubling the mass, doubling c, or doubling the temperature change each doubles the energy required. The specific heat c is the material's own property — a measure of how stubbornly it resists changing temperature — and it is why a metal pan heats in seconds while the water inside it takes minutes.
How to use this calculator
Enter the mass in grams, the specific heat capacity in J/g·°C, and the temperature change in °C. The result is the heat energy in joules, with kilojoules shown too. Water's c is 4.18 J/g·°C. For reaction efficiency work, try the percent yield calculator.
- ΔT is a difference, not a temperature. Heating from 20 °C to 40 °C means entering 20, not 40.
- °C and K are interchangeable here, because a change of one degree is the same size on both scales.
- Kilograms need converting to grams when c is quoted in J/g·°C.
Worked example
To heat 100 g of water by 20 °C: Q = 100 × 4.18 × 20 = 8360 J (8.36 kJ). Substances with a higher specific heat need more energy for the same temperature rise. The joule here is the same unit used for mechanical work, which is exactly what let Joule connect the two.
Frequently asked questions
- What is specific heat capacity?
- It is the energy needed to raise the temperature of one gram of a substance by one degree Celsius (J/g·°C).
- What is the specific heat of water?
- Liquid water has a specific heat of about 4.18 J/g·°C, one of the highest of common substances.
- What units does Q come out in?
- With mass in grams, c in J/g·°C and ΔT in °C, the heat energy Q is in joules (J).
- Can ΔT be negative?
- Yes — a negative temperature change gives a negative Q, meaning the substance released heat as it cooled.
- Does this work when the substance melts or boils?
- No. Q = mcΔT only covers heating within a single phase. During melting or boiling the temperature stays constant while energy goes into the phase change, so you need the latent heat formula Q = mL for that stage and must split the calculation into steps.