Joules to Calories Converter Calculator

Q: What is the difference between calories and Calories?

A small calorie (cal) raises the temperature of 1 gram of water by 1°C. A food Calorie (Cal) equals 1 kilocalorie (kcal) which is 1000 small calories.

Q: Which conversion constant should I use?

Use the thermochemical value 1 cal = 4.184 J for most applications. Other definitions such as 4.1868 J are historical and differ only slightly.

Q: How do I convert kilojoules directly to kilocalories?

For thermochemical convention use 1 kcal = 4.184 kJ. Therefore kilocalories equal kilojoules divided by 4.184.

Q: Why do my results differ slightly from other sources?

Small differences come from different calorie definitions or rounding choices. Using 4.184 versus 4.1868 J per cal produces tiny variations.

Q: Does this tool handle batch inputs?

Yes. Paste multiple numbers separated by spaces newlines or commas. Each entry uses the same unit and settings.

Q: Can I share a prefilled link with my settings?

Yes. Use the Share link button to copy a URL with the current inputs for easy reuse.

Q: Are food labels based on Calories or kilojoules?

Labels commonly show Calories which equal kilocalories. Many regions also show kilojoules alongside.

Energy value

Please enter a number.

Input unit

Calorie convention

Precision (decimals)

Scientific notation

Batch convert (optional) Each entry uses the same unit and settings. Non numeric tokens will be flagged.

Convention: Thermochemical

Reference constants

Thermochemical: 1 cal = 4.184 J
International Steam Table: 1 cal = 4.1868 J
15°C calorie: 1 cal = 4.18580 J

These differences rarely matter beyond several decimal places.

Quick tips

Toggle scientific notation for very small or large values.
Use the batch box for multiple measurements.
Share your configuration with a direct link.

Frequently Asked Questions

1) What is the difference between calories and Calories?

A small calorie (cal) is the heat required to raise 1 gram of water by 1°C. A food Calorie (Cal) equals 1 kilocalorie (kcal) which is 1000 small calories.

2) Which conversion constant should I use?

For science and nutrition the thermochemical value 1 cal = 4.184 J is widely accepted. The other options represent historical standards with tiny numerical differences.

3) How do I convert kilojoules directly to kilocalories?

Use 1 kcal = 4.184 kJ for the thermochemical convention. So kcal = kJ ÷ 4.184.

4) Why do my results differ slightly from other sources?

Differences usually arise from using 4.184 versus 4.1868 J per calorie or rounding to different decimal places.

5) Does this tool handle batch inputs?

Yes. Paste several numbers separated by spaces newlines or commas. Each entry uses the same unit and settings.

6) Can I share a prefilled link with my settings?

Yes. Use the Share link button to copy a URL that preserves your current inputs.

7) Are food labels based on Calories or kilojoules?

Labels typically show Calories which equal kilocalories. Some regions also display kilojoules.