Thermal Energy Calculator — Q = mcΔT and Q = mL
Find the heat transferred to or from a substance — either for a temperature change (sensible heat Q = mcΔT) or for a phase change such as melting or boiling (latent heat Q = mL). Results are shown in joules, kilojoules, kilocalories, and kilowatt-hours.
Heat type
kg
J/(kg·K)
K
Q = m × c × ΔT
- 1
Intermediate m × c
1 × 4,186 = 4,186 - 2
Thermal energy Q = (m × c) × ΔT
4,186 × 20 = 83,720
How does this calculator work?
Thermal energy for a temperature change is Q = m·c·ΔT (mass × specific heat × temp change). For a phase transition at constant temperature it is Q = m·L (mass × specific latent heat). Enter mass, the appropriate material constant, and the temperature change or phase-change type to get Q in joules, kJ, kcal, and kWh.
Formula
How this is calculated
When a substance absorbs or releases heat without changing phase, its temperature rises or falls. The sensible heat formula Q = m·c·ΔT calculates how much energy (Q) is transferred, given mass m in kilograms, specific heat capacity c in J/(kg·K), and temperature change ΔT in kelvin (numerically equal to °C difference). A positive ΔT means heating; a negative ΔT means cooling and Q comes out negative.
During a phase change (melting, freezing, boiling, or condensing) the temperature stays constant while energy goes into breaking or forming molecular bonds. The latent heat formula Q = m·L uses the specific latent heat L in J/kg for the particular material and transition. For water, the latent heat of fusion (ice ↔ liquid) is about 334 000 J/kg, and the latent heat of vaporisation (liquid ↔ steam at 100 °C) is about 2 260 000 J/kg.
The calculator converts the result to kJ, kcal, and kWh for practical comparison. Specific heat values are temperature-dependent in real materials; the values given in the hint (e.g. water 4186 J/kg·K) apply near room temperature or 15 °C.
Frequently asked questions
Sensible heat causes a measurable temperature change (Q = mcΔT) and can be felt. Latent heat is energy absorbed or released during a phase change (melting, boiling) where temperature stays constant — the energy breaks or forms intermolecular bonds rather than speeding up molecules.
Water molecules form hydrogen bonds that absorb considerable energy to break. Its specific heat capacity (~4186 J/kg·K) is among the highest of common liquids, which is why large bodies of water moderate coastal climates and why water is widely used as a coolant.
Yes. A temperature difference of 1 K equals a difference of 1 °C, so ΔT is numerically identical in both scales. The formula is the same whether you subtract in kelvin or in Celsius.
Also known as
TG we-Calculate Editorial Team. (2026). Thermal Energy Calculator — Q = mcΔT and Q = mL [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/thermal-energy-calculator
TG we-Calculate Editorial Team. "Thermal Energy Calculator — Q = mcΔT and Q = mL." TG we-Calculate. 2026. https://we-calculate.com/calculator/thermal-energy-calculator.
TG we-Calculate Editorial Team, "Thermal Energy Calculator — Q = mcΔT and Q = mL," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/thermal-energy-calculator
@misc{wecalculate_thermal_energy_calculator, title = {Thermal Energy Calculator — Q = mcΔT and Q = mL}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/thermal-energy-calculator}}, year = {2026}, note = {TG we-Calculate} }
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