Specific heat capacity calculator

Q = mcΔT, solved for whichever quantity you leave blank. Your syllabus might write it Q = mcΔθ and might work in J/kg·K or J/g·°C, so both are supported here rather than assuming one.

Units your syllabus uses

A temperature change of 1 K is exactly the same size as a change of 1 °C, so those are interchangeable here. Only the mass unit really changes the number.

Material (optional shortcut)

Boards differ on water: AQA and Edexcel GCSE papers state 4200 J/(kg·K), while general physics references and the IB data booklet use 4180. Both are here because mark schemes are keyed to the board’s own figure. Check your data sheet.

Q · energy (J)

m · mass (kg)

c · specific heat (J/kg·K)

ΔT · temperature change

Leave exactly one blank. A negative ΔT means the substance is cooling, which gives a negative Q: energy leaving rather than entering.

What specific heat capacity means

Specific heat capacity is how much energy it takes to raise the temperature of one kilogram of a substance by one degree. Water's value is 4180 J/(kg·K), which is unusually high. That single number explains a lot: why it takes so long to boil a kettle, why coastal places have milder weather than inland ones, and why water is used as a coolant in car engines.

Compare that with copper at 385 J/(kg·K). Put the same energy into equal masses of water and copper and the copper gets more than ten times hotter, because it takes far less energy to shift its temperature.

The mistake to avoid: ΔT is a temperature change, not a temperature. If something goes from 20 °C to 80 °C, ΔT is 60, not 80. Always subtract the starting temperature from the final one.

Where the formula stops working

Q = mcΔT only applies while the substance is staying in the same state. During melting or boiling, the temperature does not change at all even though energy is going in, because that energy is breaking bonds rather than speeding particles up. ΔT is zero, so this equation would wrongly predict that no energy is needed.

For those parts you need latent heat instead, Q = mL. A full "ice to steam" question is normally several sections: heat the ice, melt it, heat the water, boil it, heat the steam. Each section uses one formula or the other.

Common questions

Is it Δθ or ΔT?: Both mean the same thing: change in temperature. UK exam boards often write Δθ using the Greek letter theta, while US and many international courses write ΔT. The equation is identical either way.
Should ΔT be in Celsius or kelvin?: Either, because this is a change, not an absolute value. A rise of 10 °C is exactly a rise of 10 K, since the two scales have the same size degree. That is only true for differences: for absolute temperature, such as in the ideal gas law, you must use kelvin.
Why does my textbook say 4.18 instead of 4180?: Different units. Water is 4180 J/(kg·K) or equivalently 4.18 J/(g·°C), since a kilogram is a thousand grams. Both are correct. Use the unit selector above so the calculator matches your data sheet.
What does a negative answer mean?: That energy is leaving the substance rather than entering it, which is what happens when something cools. The size of the number is the amount of energy transferred; the sign just tells you the direction.