Specific Heat Calculator
Q = mcΔT solved for heat, mass, specific heat or final temperature, with a sourced table of specific heats (water 4186, copper 385 J/kg·K) and J, kcal or kWh output.
Specific Heat Calculator: with the default inputs, heat energy q is 334.88 kJ.
Not used when solving for mass.
Not used when solving for final temperature.
Positive = heat added, negative = removed. Used when solving for mass, specific heat or final temperature.
Positive means heat added to the substance.
- Solved for
- Q = 334,880 J = 334.88 kJ = 80.038 kcal
- Temperature change ΔT (°C or K)
- 80A change of 1 °C is a change of 1 K, so ΔT is the same in both.
- Temperature change ΔT (°F)
- 144
- Final temperature
- 100 °C
- Mass
- 1 kg
- Specific heat used (J/(kg·K))
- 4,186
- Heat capacity of this sample (J/K)
- 4,186m × c: energy to warm the whole sample by 1 K.
Assumptions
- No phase change within the temperature range.
- Specific heat is constant over the range (tabulated room-temperature values).
- No heat lost to the surroundings — all Q goes into the substance.
| Substance | J/(kg·K) | cal/(g·°C) | Heat for this mass and ΔT (kJ) |
|---|---|---|---|
| Water (liquid) | 4,186 | 1 | 334.88 |
| Ice (−10 °C) | 2,090 | 0.5 | 167.2 |
| Steam (100 °C) | 2,010 | 0.48 | 160.8 |
| Ethanol | 2,440 | 0.583 | 195.2 |
| Air (constant pressure) | 1,005 | 0.24 | 80.4 |
| Wood | 1,700 | 0.406 | 136 |
| Concrete | 880 | 0.21 | 70.4 |
| Glass | 840 | 0.201 | 67.2 |
| Granite | 790 | 0.189 | 63.2 |
| Aluminum | 897 | 0.214 | 71.76 |
| Iron / steel | 449 | 0.107 | 35.92 |
| Copper | 385 | 0.092 | 30.8 |
| Brass | 380 | 0.091 | 30.4 |
| Silver | 235 | 0.056 | 18.8 |
| Mercury | 140 | 0.033 | 11.2 |
| Gold | 129 | 0.031 | 10.32 |
| Lead | 128 | 0.031 | 10.24 |
Values from the HyperPhysics specific-heat table; water from the NIST Chemistry WebBook (4.18 J/(g·K) at 25 °C). Specific heat varies a few percent with temperature.
How this is worked out
The formula
Q = m × c × ΔT Q = heat energy transferred (J) m = mass (kg) c = specific heat capacity (J/(kg·K)) ΔT = T_final − T_initial (K or °C — the change is the same) Rearranged: m = Q/(cΔT), c = Q/(mΔT), ΔT = Q/(mc)
Open How it’s calculated above to see this worked through with your own numbers.
What you enter
- Solve for
- Choose one of 4 options.Heat energy (Q) · Mass (m) · Specific heat (c) — e.g. from a calorimetry experiment · Final temperature
- Mass
- Not used when solving for mass.in kg · 0 or more · defaults to 1
- Substance
- Choose one of 18 options.Water (liquid) — 4186 J/(kg·K) · Ice (−10 °C) — 2090 J/(kg·K) · Steam (100 °C) — 2010 J/(kg·K) · Ethanol — 2440 J/(kg·K) · Air (constant pressure) — 1005 J/(kg·K) · Wood — 1700 J/(kg·K) · Concrete — 880 J/(kg·K) · Glass — 840 J/(kg·K) · Granite — 790 J/(kg·K) · Aluminum — 897 J/(kg·K) · Iron / steel — 449 J/(kg·K) · Copper — 385 J/(kg·K) · Brass — 380 J/(kg·K) · Silver — 235 J/(kg·K) · Mercury — 140 J/(kg·K) · Gold — 129 J/(kg·K) · Lead — 128 J/(kg·K) · Custom (enter below)
- Custom specific heat(under More options)
- Used when Substance is Custom. 1 cal/(g·°C) = 4,184 J/(kg·K); 1 BTU/(lb·°F) = 4,186.8 J/(kg·K).0 or more · defaults to 4186
- Initial temperature
- A number.in °C · -273.15 or more · defaults to 20
- Final temperature
- Not used when solving for final temperature.in °C · -273.15 or more · defaults to 100
- Heat energy (Q)
- Positive = heat added, negative = removed. Used when solving for mass, specific heat or final temperature.in kJ · defaults to 334.88
What you get back
- Heat energy Qmain answer
- Positive means heat added to the substance.
- Solved for
- Temperature change ΔT (°C or K)
- A change of 1 °C is a change of 1 K, so ΔT is the same in both.
- Temperature change ΔT (°F)
- Final temperature
- Mass
- Specific heat used (J/(kg·K))
- Heat capacity of this sample (J/K)
- m × c: energy to warm the whole sample by 1 K.
What this assumes
- No phase change within the temperature range.
- Specific heat is constant over the range (tabulated room-temperature values).
- No heat lost to the surroundings — all Q goes into the substance.
About this calculator
Specific heat is the energy it takes to warm one kilogram of a substance by one kelvin, and Q = mcΔT is how you scale that to any mass and any temperature change. It answers the practical questions — how much energy to boil a kettle, how long a 2 kW heater takes to warm a bath, why a copper pan heats fast and a cast-iron one holds heat — and the lab ones, where you measure Q and ΔT to identify a metal from its specific heat. Choose what to solve for, pick the substance (or enter a custom c under More options), and enter the temperatures in °C, °F or K.
Reading the results
- Heat energy Q is positive when energy flows into the substance (it warms) and negative when it flows out. Switch the unit to kcal or kWh — 1 kWh is 3,600 kJ, and a food calorie is 4.184 kJ.
- ΔT is a difference, so it is the same number in °C and K; in °F multiply by 1.8. The calculator shows both.
- Heat capacity (m × c, in J/K) is the whole sample's value; it is what thermal-mass and calorimetry calculations use.
- The table shows how much energy the same mass and ΔT would need for other materials — water's 4,186 J/(kg·K) is exceptionally high, which is why it moderates coastal climates and makes a good coolant.
Common mistakes
- Phase changes. Q = mcΔT works only while the substance stays in one phase. Heating water from 20 °C to steam at 100 °C needs 335 kJ/kg to reach the boil and then another 2,256 kJ/kg to vaporize it — nearly seven times more. The calculator warns when your temperatures cross 0 °C or 100 °C for water.
- Units of c. Tables quote J/(g·°C), cal/(g·°C), J/(kg·K) and BTU/(lb·°F). Water is 1.00 cal/(g·°C) = 4.184 J/(g·°C) = 4,184 J/(kg·K) = 1.00 BTU/(lb·°F). The custom field takes J/(kg·K).
- Kelvin conversion of ΔT. Never add 273.15 to a temperature difference.
Where it breaks
Specific heat is not truly constant: water's varies about 1% between 0 and 100 °C, gases differ between constant pressure (c_p) and constant volume (c_v), and near phase transitions or at cryogenic temperatures the value changes sharply. For everyday ranges the tabulated values are good to a few percent.
Frequently asked questions
▸What is the specific heat formula?
Q = mcΔT: heat energy equals mass times specific heat capacity times the temperature change. With m in kg, c in J/(kg·K) and ΔT in K (or °C), Q is in joules.
▸What is the specific heat of water?
About 4,186 J/(kg·K), or 1 cal/(g·°C) — the calorie was defined from it. That is high compared with most materials: aluminum is 897, iron 449, copper 385, gold 129.
▸How much energy does it take to boil a liter of water?
From 20 °C, 1 kg × 4,186 × 80 = 335 kJ (0.093 kWh) to reach 100 °C. Actually turning it all to steam needs a further 2,256 kJ of latent heat, which Q = mcΔT doesn't cover.
▸Do I use kelvin or Celsius for ΔT?
Either — a change of 1 °C is exactly a change of 1 K, so the difference is the same number. Only convert if you are using Fahrenheit (divide a °F change by 1.8).
▸How do I find the specific heat of an unknown metal?
Heat a known mass of it, drop it into a known mass of water, and measure the temperature changes. The heat lost by the metal equals the heat gained by the water; use the solve-for-c mode with the metal's mass, its ΔT and the Q computed for the water.
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