Enthalpy Change Calculator (ΔH = mcΔT)
Calculate the enthalpy change (heat transferred) when a substance is heated or cooled. Enter mass, material, and temperature change — the calculator applies ΔH = m × cₚ × ΔT with built-in specific heat values for common materials.
g
Material
°C
°C
Endothermic — heat absorbed from surroundings
- 1
Temperature change ΔT
T₂ − T₁ = 100 − 20 = 80 °C - 2
Heat transferred Q = m × cₚ × ΔT
100 g × 4.186 J/g·°C × 80 = 33,488 J - 3
Enthalpy change ΔH = Q ÷ 1000
33,488 ÷ 1000 = 33.488Divide by 1000 to convert from joules to kilojoules.
How does this calculator work?
Enthalpy change during a temperature shift is ΔH = m × cₚ × ΔT. For 100 g of water (cₚ = 4.186 J/g·°C) heated from 20 °C to 100 °C: ΔH = 100 × 4.186 × 80 = 33,488 J ≈ 33.5 kJ (endothermic). Positive ΔH = heat absorbed; negative = released. Latent heat at phase transitions must be calculated and added separately.
Formula
How this is calculated
At constant pressure, enthalpy change (ΔH) equals the heat transferred: ΔH = m × cₚ × ΔT, where m is mass in grams, cₚ is the specific heat capacity at constant pressure in J/(g·°C), and ΔT = T₂ − T₁ in degrees Celsius (a Celsius temperature difference equals the same Kelvin difference). Positive ΔH means the system absorbed heat from the surroundings (endothermic); negative ΔH means it released heat (exothermic).
The specific heat values in this calculator are standard reference values at approximately 25 °C and 1 atm (2024 reference data, widely cited): water 4.186 J/g·°C; ice 2.09; steam 2.01; ethanol 2.44; aluminium 0.900; iron/steel 0.450; copper 0.385; gold 0.128 J/g·°C. cₚ does vary with temperature and pressure, so these are editable estimates — use the Custom option to enter a more precise value for your application.
Important limitation: this formula covers only sensible heat — the energy required for a temperature change within a single phase. It does not include latent heat at phase changes (melting or boiling). To model ice heated from −20 °C to steam at 120 °C, you must add separate latent-heat terms: ice→water 334 J/g at 0 °C, water→steam 2260 J/g at 100 °C, plus three ΔH = mcΔT segments in between.
Frequently asked questions
At constant pressure, heat transferred to or from a system equals its enthalpy change (q = ΔH). Most lab reactions and everyday heating occur at constant atmospheric pressure, so the terms are effectively interchangeable there. At constant volume, heat equals the change in internal energy (ΔU), not enthalpy.
Water's cₚ of 4.186 J/g·°C is unusually high because of extensive hydrogen bonding. A large amount of energy is needed before the temperature rises, because much of the heat reorganises hydrogen bonds rather than directly increasing molecular kinetic energy. This makes water an effective thermal buffer and coolant.
Use ΔH = m × L, where L is the specific latent heat of fusion (melting) or vaporisation (boiling). For water: L_fusion = 334 J/g at 0 °C; L_vaporisation = 2260 J/g at 100 °C. Add these to the mcΔT segments for multi-phase calculations.
Also known as
TG we-Calculate Editorial Team. (2026). Enthalpy Change Calculator (ΔH = mcΔT) [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/enthalpy-calculator
TG we-Calculate Editorial Team. "Enthalpy Change Calculator (ΔH = mcΔT)." TG we-Calculate. 2026. https://we-calculate.com/calculator/enthalpy-calculator.
TG we-Calculate Editorial Team, "Enthalpy Change Calculator (ΔH = mcΔT)," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/enthalpy-calculator
@misc{wecalculate_enthalpy_calculator, title = {Enthalpy Change Calculator (ΔH = mcΔT)}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/enthalpy-calculator}}, year = {2026}, note = {TG we-Calculate} }
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