Physics · Heat
Specific heat calculator.
Find the heat needed to change an object’s temperature, or the final temperature when a hot and a cold substance are mixed in an insulated container.
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Specific heat and calorimetry formulas
The heat needed to change an object's temperature is Q = m × c × ΔT, where c is the specific heat. In SI units c is in J/(kg·K) and equals the heat needed to warm 1 kg by 1 °C (OpenStax). Water's value of 4.186 J/g·°C, or 4186 J/(kg·K), is higher than any other common substance (HyperPhysics), which is why water so strongly moderates temperature. The relation fails if the substance melts or boils on the way.
Worked example. Warming 2 kg of water from 20 °C to 80 °C: Q = 2 × 4186 × 60 = 502,320 J, or 502.32 kJ.
Mixing. In an isolated container the heat lost by the hotter object equals the heat gained by the colder one, Qhot + Qcold = 0 (OpenStax), so Tf = (m1c1T1 + m2c2T2) ÷ (m1c1 + m2c2). Dropping 0.2 kg of aluminum at 100 °C into 0.5 kg of water at 20 °C gives Tf = 26.335 °C.
Specific heats in the presets are HyperPhysics values at 20 °C and drift with temperature. This is a classroom model, not for cooking, process, medical or safety calculations.
Frequently asked questions
What is the specific heat formula?
Q = m × c × ΔT. For 2 kg of water warmed by 60 °C, Q = 502,320 J.
What is the specific heat of water?
4186 J/(kg·K), the same as 4.186 J/(g·°C) or about 1 calorie per gram per degree Celsius (HyperPhysics).
How do I find the final temperature of two mixed substances?
Set the heat lost by the hot one equal to the heat gained by the cold one. The example gives 26.335 °C.
Does this include melting or boiling?
No. Phase changes absorb or release heat without changing the temperature and need latent heat, which is not included.
Can I use Celsius or Kelvin?
Either, because a change of 1 °C equals a change of 1 K. Enter both temperatures in the same scale.
Sources
Checked
- OpenStax University Physics Volume 2, 1.4 Heat Transfer, Specific Heat, and Calorimetry
- HyperPhysics: Table of Specific Heats (at 20 C)
- HyperPhysics: Specific Heat
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Scope
Idealised textbook model with no heat loss. Not for cooking, process, medical or safety calculations. Results are arithmetic from the formulas shown, for study and general interest, and not professional or engineering advice.