BYTETOOLS

Specific Heat Calculator

Solve Q = mcΔT for heat, mass, specific heat capacity or temperature change, with a 22-material table and a separate phase-change term Q = mL.

41,840 J
Heat energy Q

Q = m · c · ΔT

  • Q = 0.5 kg × 4,184 J/(kg·K) × 20 K = 41,840 J
  • 41,840 J = 41.84 kJ = 10,000 cal = 10 kcal = 39.6567 BTU = 11.6222 Wh
  • A positive ΔT means heat goes in and the substance warms up.
  • A 2 kW kettle element would supply this in 20.92 seconds.

Phase change — Q = m · L

Q = m · L = 100 g × 334 J/g = 33,400 J (33.4 kJ, 7.9828 kcal)

A phase change happens at constant temperature, so Q = mcΔT does not apply during it — you need this separate term. Melting 100 g of ice at 0 °C takes 33.4 kJ, which is roughly the same as heating that water from 0 °C all the way to 80 °C.

Specific heat capacity varies with temperature and, for gases, with whether the pressure or the volume is held constant — the table values above are typical figures near room temperature and atmospheric pressure. Worked example: heating 500 g of water by 20 °C needs 500 × 4.184 × 20 = 41 840 J, which is 41.84 kJ or 10 kcal.

What is the Specific Heat Calculator?

The heat needed to change a substance's temperature is Q = m·c·ΔT, where c is the specific heat capacity. Heating 500 g of water by 20 °C takes 500 × 4.184 × 20 = 41,840 J, which is 41.84 kJ or 10 kcal.

  • Solves Q = mcΔT for Q, m, c or ΔT with the working shown
  • Table of 22 materials with specific heats near room temperature
  • Temperature as a change or as a start and end pair, in °C, K or °F
  • Capacity units including J/(g·°C), J/(kg·K), cal/(g·°C) and BTU/(lb·°F)
  • Separate latent heat panel for fusion and vaporization, Q = m·L
  • Runs entirely in your browser with no data sent to a server

How to use the Specific Heat Calculator

  1. 1

    Choose what to solve for: heat energy, mass, specific heat capacity or temperature change.

  2. 2

    Pick a material to load its specific heat, or type your own value and unit.

  3. 3

    Enter the mass and either the temperature change or a start and end temperature.

  4. 4

    Read the answer, which you can display in joules, kilojoules, calories, kWh or BTU.

  5. 5

    Use the phase-change panel for melting or boiling, where Q = m·L applies instead.

About the Specific Heat Calculator

The ByteTools Specific Heat Calculator rearranges Q = m·c·ΔT four ways, so you can find the heat needed, the mass being heated, the specific heat capacity of an unknown sample or the temperature change a given amount of energy produces. A material dropdown covers 22 common substances from water at 4.184 J/(g·°C) down to lead at 0.129, and any value can be overridden.

Temperatures can be entered as a change or as a start and end pair, in °C, K or °F, and the tool treats them as differences rather than absolute readings, so a change of 1 °C correctly equals a change of 1 K. Mass, energy and capacity each have their own unit dropdown, including J/(kg·K), cal/(g·°C) and BTU/(lb·°F).

A separate panel handles melting and boiling with Q = m·L, because a phase change happens at constant temperature and Q = mcΔT does not apply during it. All of this runs in your browser in JavaScript, with nothing uploaded and nothing stored, so it works offline once the page has loaded.

Frequently asked questions

What is the formula for specific heat?

The heat transferred is Q = m·c·ΔT, where m is the mass, c is the specific heat capacity and ΔT is the temperature change. Rearranged, c = Q ÷ (m·ΔT), which is how an unknown material is identified in a calorimetry experiment.

What is the specific heat capacity of water?

Liquid water is 4.184 J per gram per °C, equivalent to 4184 J/(kg·K) or 1 cal/(g·°C). That is unusually high, which is why water is such an effective coolant and why the sea moderates coastal temperatures.

How much energy does it take to boil water?

Heating and boiling are two separate steps. Raising 1 kg of water from 20 °C to 100 °C takes about 335 kJ from Q = mcΔT, and then turning it all to steam takes a further 2260 kJ from the latent heat of vaporization, Q = mL.

Why does a phase change need a different formula?

During melting or boiling the temperature stays constant while the energy goes into breaking bonds instead, so ΔT is zero and Q = mcΔT gives zero. The latent heat term Q = m·L covers that stage, and this tool provides it in a separate panel.

Do the table values change with temperature?

Yes. Specific heat capacity varies with temperature and, for gases, with whether pressure or volume is held constant, so the listed figures are typical values near room temperature and atmospheric pressure. For precise work at extreme temperatures, look up a value for your actual conditions.

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