Kilocalorie (kcal)

Definition

One thousand thermochemical calories (4184 J) — the "Calorie" on food labels.

History

The kilocalorie is one thousand calories, where the calorie was defined as the heat needed to warm one gram of water by one degree Celsius. On food labels the capitalised Calorie is really a kilocalorie.

Where it is used

Kilocalories, shown as Calories, measure food energy on US and many other nutrition labels.

Typical uses include nutrition and diet, food labels.

Conversion pages

These pages convert kilocalorie to or from another unit in energy.

• Kilocalorie to kilojoule

Other Energy units

• Kilojoule (kJ)
• Calorie (cal)
• Joule (J)
• Kilowatt-hour (kWh)
• British thermal unit (BTU)
• Watt-hour (Wh)

Sources

• NIST SP 811 NIST SP 811, Appendix B; ISO 80000-5 (energy) · Dataset reviewed Nov 11, 2026