Specific Heat Converter
Convert specific heat capacity between J/g·°C, J/kg·K, kJ/kg·K, cal/g·°C, and BTU/lb·°F. Enter a value and choose the From unit and To unit.
Convert Specific Heat Capacity Between Units
Specific Heat Conversion Formula
Where:
- \(c_{\mathrm{from}}\) — the value entered in the From unit
- \(c_{\mathrm{to}}\) — the converted value in the To unit
- \(F_{\mathrm{from}}\) and \(F_{\mathrm{to}}\) — the calculator’s factors for converting each unit to J/kg·K
The calculator first converts the entered value to J/kg·K, then divides by the factor for the selected output unit. Its factors are listed below; the BTU/lb·°F factor requires particular caution.
Specific Heat – Calculation Example
Example: convert the default value of 4.18 J/g·°C to kJ/kg·K.
Both units have a conversion factor of 1,000 relative to J/kg·K:
\[4.18\times1{,}000=4{,}180\ \mathrm{J/(kg\cdot K)}\]
\[4{,}180\div1{,}000=4.18\ \mathrm{kJ/(kg\cdot K)}\]
Result: 4.18 kJ/kg·K.
How to use the calculator
- Enter the number you want to convert in Specific heat value. The field accepts zero and positive values.
- Select the unit attached to that number in From unit. The default is J/g·°C.
- Select the unit you need in To unit. The default is kJ/kg·K.
- Read Converted Specific Heat, which displays the converted number and its unit. The result is rounded to eight decimal places.
Choose the units based on how your source and destination express specific heat, not on the temperature at which a measurement was made. For example, a value stated in J/g·°C belongs in the J/g·°C input option even if the substance was measured at a particular temperature in kelvin.
What specific heat capacity means
Specific heat capacity describes how much energy is needed to raise the temperature of a unit mass of a substance by one degree, under stated conditions. A larger value means more energy is needed for the same mass and temperature rise. For a simple calculation with approximately constant specific heat, heat added can be estimated using \(Q=mc\Delta T\), where \(Q\) is heat, \(m\) is mass, \(c\) is specific heat capacity, and \(\Delta T\) is the temperature change.
Specific heat is expressed per unit mass and per unit of temperature change. A change of one degree Celsius has the same size as a change of one kelvin, so converting between J/g·°C and J/kg·K changes the mass scale but not the size of the temperature increment. Likewise, J/g·°C and kJ/kg·K have the same numerical value: multiplying the energy and mass units by 1,000 cancels out.
Consistent units matter when comparing material data or using a specific heat value in a heat calculation. If mass is in kilograms, temperature change is in kelvin, and energy is required in joules, use a value in J/kg·K. Specific heat is not the same as thermal conductivity, which concerns the transfer of heat through a material, or thermal expansion, which concerns changes in size with temperature.
Conversion factors and practical limits
The table shows the factors programmed into this calculator. Multiply a value in the listed unit by its factor to obtain the calculator’s intermediate value in J/kg·K.
| From unit | Calculator factor to J/kg·K |
|---|---|
| J/g·°C | 1,000 |
| J/kg·K | 1 |
| kJ/kg·K | 1,000 |
| cal/g·°C | 4,186.8 |
| BTU/lb·°F | 2,326 |
Important BTU limitation: the calculator uses 2,326 J/kg·K for 1 BTU/lb·°F. That is not the conventional physical conversion, which is approximately 4,187 J/kg·K for 1 BTU per pound per degree Fahrenheit, depending on the BTU definition. Therefore, results involving BTU/lb·°F should not be used for engineering or other work requiring an accurate conversion. The discrepancy is in the calculator’s factor, not a rounding difference.
The calculator uses 4,186.8 J/kg·K for 1 cal/g·°C. Calorie definitions can differ slightly, so check the definition used by your source when precision matters. The other listed metric factors follow directly from the stated mass and energy prefixes.
A unit conversion does not establish which specific heat value applies to a material. Specific heat can vary with temperature, pressure, composition, and phase; tables may also distinguish heat capacity at constant pressure from heat capacity at constant volume. Confirm that the source value matches the conditions of your calculation before using it in a heat transfer analysis. If a process crosses a phase change, a single specific heat value alone does not account for the energy involved in that change.
Frequently Asked Questions
How can I convert specific heat capacity by hand?
Convert the energy and mass units separately, then account for the size of the temperature interval. For example, one calorie is 4.1868 joules, so \(1\ \mathrm{cal/(g\cdot{}^\circ C)}\) is approximately \(4.1868\ \mathrm{J/(g\cdot{}^\circ C)}\). To express that result per kilogram, multiply by 1,000. Check which definition of the calorie your source uses if precision matters.
What is a typical specific heat capacity?
Liquid water is often approximated as 4.18 J/g·°C near room temperature. For comparison, aluminum is about 0.90 J/g·°C and copper about 0.39 J/g·°C. These are reference values, not targets or universal constants: temperature, composition, and measurement conditions can change the value. Check a material-specific source for design work.
Can I use the BTU/lb·°F results for engineering calculations?
No. This calculator’s BTU/lb·°F factor differs substantially from the conventional conversion, so results converted either to or from that unit may be wrong for engineering purposes. Conventionally, 1 BTU/lb·°F is approximately 4.187 kJ/kg·K, with a small variation depending on the BTU definition. Use a verified conversion source when accuracy matters.
Why does a Fahrenheit temperature interval need a conversion factor?
A change of 1 °F is smaller than a change of 1 °C or 1 K: it equals 5/9 of either interval. Specific heat is energy per unit of temperature change, so the interval size affects its numerical value. Do not add or subtract 32 when converting specific heat; that offset applies to absolute temperature readings, not temperature differences.
Is specific heat capacity the same as heat capacity or molar heat capacity?
No. Specific heat capacity is stated per unit mass, while heat capacity applies to an entire object and molar heat capacity is stated per mole. For an approximately uniform object, its heat capacity is \(C=mc\), where \(m\) is its mass and \(c\) is its specific heat capacity. Converting between mass-based and molar values also requires the substance’s molar mass.
What if specific heat changes over the temperature range?
Use a temperature-dependent value or suitable average rather than assuming one tabulated number remains exact. For a substantial change in temperature, heat can be calculated by integrating specific heat over the range: \(Q=m\int_{T_1}^{T_2}c(T)\,dT\). This converter only changes units; it cannot determine how a material’s specific heat varies.
Does a zero or very small converted value mean the material has no specific heat?
Not necessarily. Zero is an allowed input and converts to zero, but an ordinary material should not be assigned zero specific heat merely because no data is available. The displayed result is rounded to eight decimal places, so a sufficiently small positive result may appear as zero. Keep the unrounded value and its measurement uncertainty for precision-sensitive work.
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