How do I calculate the heat capacity of an object?

Heat capacity C = mass × specific heat = m × c. For a 5 kg aluminum block (c = 900 J/kg·K): C = 5 × 900 = 4500 J/K. This means 4500 J raises its temperature by 1 K. For composites, sum the heat capacities of each component.

Why does heat capacity matter for thermal storage?

High heat capacity means more energy stored per degree temperature change. Water has excellent heat capacity (C = 4186 J/kg·K × mass), making it ideal for thermal storage. Phase-change materials store even more by absorbing latent heat at constant temperature.

What is thermal mass in buildings?

Thermal mass is the heat capacity of building materials—concrete, brick, water tanks. High thermal mass stabilizes indoor temperature by absorbing heat during warm periods and releasing it when cool. A 1000 kg concrete floor (c ≈ 880 J/kg·K) has C = 880 kJ/K, absorbing significant energy with minimal temperature change.

How is heat capacity measured experimentally?

Using calorimetry: add known heat Q and measure temperature change ΔT. Heat capacity C = Q/ΔT. Common methods include electrical heating calorimeters (Q = V×I×t), mixing calorimeters, and differential scanning calorimetry (DSC) for precise measurements of small samples.

Capacité thermique Converter

About Heat Capacity Conversion

Heat capacity measures the amount of heat required to change an object's temperature by one degree—joules per kelvin for the entire object, not per unit mass. This extensive property depends on both the material and the total amount present: a bathtub of water has much higher heat capacity than a cup, even though both contain water with identical specific heat. Heat capacity directly determines how much a system's temperature changes when absorbing or releasing energy.

The SI unit is joules per kelvin (J/K). Heat capacity is fundamental for thermal mass calculations in building design (passive solar homes, thermal flywheel effects), calorimetry experiments (measuring reaction energies), temperature control systems, and determining energy storage potential. The relationship Q = C × ΔT makes calculations straightforward: heat transferred equals heat capacity times temperature change.

Our converter handles heat capacity units used in thermodynamics, calorimetry, and thermal engineering applications.

Common Heat Capacity Conversions

From	To	Multiply By
J/K	J/°C	1
J/K	kJ/K	0.001
kJ/K	J/K	1,000
J/K	cal/°C	0.239
cal/°C	J/K	4.184
J/K	BTU/°F	5.266 × 10⁻⁴
BTU/°F	J/K	1,899
kJ/K	kcal/°C	0.239
kcal/°C	kJ/K	4.184
kJ/K	BTU/°F	0.5266

Heat Capacity Unit Reference

Joule per kelvin (J/K) – The SI unit for heat capacity, representing the energy required to raise an object's temperature by 1 K (equivalently, 1 °C). This extensive property scales with system size: doubling the mass doubles the heat capacity. Values can range from millijoules per kelvin for small laboratory samples to megajoules per kelvin for building thermal mass. Scientific calorimetry and international engineering standards use this unit.

Calorie per degree Celsius (cal/°C) – Traditional unit widely used before SI adoption. 1 cal/°C = 4.184 J/K (by definition of the thermochemical calorie). The calorie was historically defined so that water's specific heat equals 1 cal/g·°C at 15°C, making calorimetry calculations intuitive. Still found in chemistry literature and some educational contexts.

BTU per degree Fahrenheit (BTU/°F) – US engineering unit for heat capacity, standard in HVAC design, building thermal analysis, and American industrial applications. 1 BTU/°F = 1899 J/K. Building thermal mass specifications, heating system calculations, and US energy audits commonly use this unit. Water has a heat capacity of 1 BTU/lb·°F, which simplifies water-based heating calculations.

Kilojoule per kelvin (kJ/K) – Convenient for larger systems where J/K would give unwieldy numbers. Common for building thermal mass calculations, industrial process vessels, and thermal storage systems. 1 kJ/K = 1000 J/K. A typical residential water heater tank might have heat capacity around 500 kJ/K.