Specific Heat Converter

J/kg·K · kJ/kg·K · BTU/lb·°F · cal/g·°C · kcal/kg·°C

Convert specific heat capacity units instantly between J/kg·K, kJ/kg·K, BTU/lb·°F, cal/g·°C, and kcal/kg·°C. Essential for chemical engineering, thermodynamics, HVAC design, and materials science.

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Quick Reference

  • 1 BTU/lb·°F = 4,186.8 J/kg·K
  • 1 cal/g·°C = 4,186.8 J/kg·K
  • Water = 4,186 J/kg·K

Conversion Table

UnitNameValue

About Specific Heat Capacity

Specific heat capacity (c) is the energy required to raise 1 kg of a substance by 1 K. It describes how well a material stores thermal energy. The SI unit is J/kg·K. Water’s unusually high value of 4,186 J/kg·K makes it ideal for cooling and heating systems.

Unit Systems

The SI system uses J/kg·K or kJ/kg·K. The imperial/US system uses BTU/(lb·°F). The calorie-based system uses cal/g·°C or kcal/kg·°C. Since 1 cal = 4.1868 J, the numerical value of BTU/lb·°F and cal/g·°C are equal — both equal 4,186.8 J/kg·K.

Reference Values — Common Materials

Water
4,186 J/kg·K
Ice
2,090 J/kg·K
Steam
2,010 J/kg·K
Air (dry)
1,005 J/kg·K
Aluminum
897 J/kg·K
Iron / Steel
449 J/kg·K
Copper
385 J/kg·K
Ethanol
2,440 J/kg·K
1 BTU/lb·°F
= 4,186.8 J/kg·K
1 kJ/kg·K
= 1,000 J/kg·K

Worked Examples

1 BTU/lb·°F to J/kg·K

Multiply by 4,186.8.
1 × 4,186.8 = 4,186.8
= 4,186.8 J/kg·K

4.186 kJ/kg·K to BTU/lb·°F

Convert to J first: 4,186 J/kg·K.
4,186 ÷ 4,186.8 = 0.99981
≈ 1.000 BTU/lb·°F

1 cal/g·°C to J/kg·K

1 cal/g·°C = 4,186.8 J/kg·K
(thermochemical calorie)
= 4,186.8 J/kg·K

2.09 J/g·K to kJ/kg·K

J/g·K = kJ/kg·K numerically.
2.09 J/g·K = 2.09 kJ/kg·K
= 2.09 kJ/kg·K

When You Need This Converter

Chemical Engineering

Calculate heat duties for reactors and heat exchangers using Q = mcΔT with consistent units.

HVAC Design

Size heating and cooling systems using BTU/lb·°F values common in US engineering practice.

Materials Science

Compare thermal properties across metals, polymers, and composites in different unit systems.

Food Processing

Use cal/g·°C for pasteurization and refrigeration calculations in food science applications.

Thermal Management

Select coolants and heat storage materials for electronics and industrial processes.

Physics Education

Convert between SI and traditional units when working problems from different textbooks.

Mental Math Tips

BTU/lb·°F to J/kg·K

Multiply by ~4,187. Water’s 1 BTU/lb·°F = 4,186.8 J/kg·K is the key anchor value.

kJ/kg·K to J/kg·K

Simply multiply by 1,000. A value of 4.186 kJ/kg·K = 4,186 J/kg·K.

cal/g·°C equals J/g·K

Numerically, 1 cal/g·°C ≈ 4.187 J/g·K = 4,187 J/kg·K. The calorie and joule differ by this factor.

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Frequently Asked Questions — Specific Heat Converter

Specific heat capacity is the amount of energy required to raise the temperature of 1 kg of a substance by 1 K (or 1°C). The SI unit is J/kg·K. It describes how much heat a material can store per unit mass per degree of temperature change.
Water’s specific heat of 4,186 J/kg·K is unusually high due to extensive hydrogen bonding between molecules. Breaking these bonds requires significant energy, making water an excellent heat storage and transfer medium used in cooling systems worldwide.
Water: 4,186 J/kg·K; Aluminum: 897 J/kg·K; Iron: 449 J/kg·K; Copper: 385 J/kg·K; Air (dry): 1,005 J/kg·K; Ethanol: 2,440 J/kg·K; Ice: 2,090 J/kg·K.
Specific heat is an intensive property — energy per unit mass per degree (J/kg·K). Heat capacity is extensive — total energy for a specific object (J/K). Heat capacity = specific heat × mass. For example, a 2 kg block of aluminum has a heat capacity of 2 × 897 = 1,794 J/K.
Divide by 4,186.8. For example, 4,186.8 J/kg·K ÷ 4,186.8 = 1 BTU/lb·°F. Equivalently, 1 BTU/lb·°F = 4,186.8 J/kg·K. This tool handles the conversion automatically.
Engineers use specific heat in the formula Q = mcΔT to calculate heat transfer, where m is mass, c is specific heat, and ΔT is temperature change. It’s essential for sizing HVAC systems, heat exchangers, boilers, and thermal energy storage.
1 cal/g·°C = 4,186.8 J/kg·K. The calorie (thermochemical) is the energy to raise 1 gram of water by 1°C. This unit is common in chemistry and food science. Interestingly, cal/g·°C and BTU/lb·°F are numerically equal — both convert to 4,186.8 J/kg·K.

All Specific Heat Conversions

Common
J/kg·K → BTU/lb·°FBTU/lb·°F → J/kg·KkJ/kg·K → J/kg·KJ/kg·K → kJ/kg·K
Full Range
J/kg·K → kJ/kg·KkJ/kg·K → J/kg·KJ/kg·K → BTU/lb·°FBTU/lb·°F → J/kg·KkJ/kg·K → BTU/lb·°FBTU/lb·°F → kJ/kg·K