Specific Heat Calculator
How much energy a temperature change really takes.
Specific Heat Calculator
Q = mass x specific heat capacity x temperature change.
Calculated instantly
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What This Calculator Does
The Specific Heat Calculator applies Q = mc delta T to find the energy needed to change the temperature of a mass. It is the basic calculation behind heating water, sizing a thermal store, and checking a cooling load.
How It Works
Mass in kilograms is multiplied by specific heat capacity in joules per kilogram per degree Celsius, then by the temperature change in degrees Celsius. The result is energy in joules. Dividing by 1,000 gives kilojoules, by 3,600,000 gives kilowatt-hours, and by 4,184 gives kilocalories. The sign of the temperature change tells you whether energy is absorbed or released.
Example
Heating 2 kg of water with a specific heat of 4,186 J/kg-C by 30 C takes 2 x 4,186 x 30 = 251,160 J. That is 251.16 kJ, about 0.0698 kWh, or about 60.0 kcal.
Formula
Q = mass x specific heat x temperature changejoules / 1000joules / 3,600,000joules / 4,184Reading the Results
Energy required
The sensible heat for the stated mass and temperature change. It excludes losses to the surroundings and any phase change.
Energy in kilowatt-hours
The same energy in the unit on an electricity bill. It is useful for comparing an electric heater or heat pump with the theoretical minimum.
Energy in kilocalories
The energy in food-calorie units, often used in nutrition and older engineering texts. One kilocalorie is 4,184 joules.
Sources and References
NIST - Thermophysical Properties of Fluid Systems
Specific heat and phase properties
Reference data for water and other fluids across temperature and pressure.
OpenStax College Physics - Temperature, Heat, and Specific Heat
Q = mc delta T derivation
A textbook treatment of specific heat and the sign convention for heating and cooling.
References identify the method or data behind this calculator. Where a standard or tariff changes, the current edition applies, and the assumptions stated above take precedence over a remembered figure.
Frequently Asked Questions
What is specific heat capacity?
The energy needed to raise one kilogram of a substance by one degree Celsius. Water is about 4,186 J/kg-C, which is high, which is why it is good at storing heat. Metals are much lower, so they heat and cool quickly.
Why does my real heater use more energy than the calculator?
The calculation gives the minimum sensible heat. Real systems lose heat to the room, the container, and the surroundings, and they may have inefficiencies in the heating element or heat pump. A poorly insulated tank can lose a large share of the input.
Does this work for cooling?
Yes. Enter a negative temperature change or take the magnitude and interpret it as energy removed. The specific heat is assumed constant over the range; for a large change, use an average value or a property table.
What about melting or boiling?
Add latent heat separately. Melting ice takes about 334 kJ per kg, and vaporising water takes about 2,260 kJ per kg at atmospheric pressure. This calculator covers only the temperature change within one phase.
Which specific heat value should I use for water?
Liquid water is about 4,186 J/kg-C near room temperature. It rises slightly with temperature, and ice and steam have much lower values. For a precise design, use a property table at the relevant temperature rather than a single constant.