How many calories are in one kilojoule?

One kilojoule equals approximately 239.006 thermochemical calories (cal). The exact factor is 1,000 ÷ 4.184, because 1 cal = 4.184 J by definition.

What type of calorie does this tool use?

This tool uses the thermochemical calorie (cal_th), defined as exactly 4.184 joules. It is NOT the food Calorie (kilocalorie, kcal), which is 1,000 times larger. To get kcal from kJ, divide by 4.184 directly.

How is this different from kilojoules to kilocalories (kcal)?

A kilocalorie (kcal, the "food Calorie") equals 1,000 thermochemical calories. To convert kJ to kcal, divide by 4.184. To convert kJ to cal (small calorie), multiply by 239.006 — that is what this tool does.

Is the 4.184 J/cal factor exact?

Yes. The thermochemical calorie is defined as exactly 4.184 joules (no rounding). A slightly different value, 4.1868 J, applies to the International Table calorie used in steam engineering, but 4.184 is correct for most science and nutrition contexts.

Why do food labels in some countries use kilojoules?

Countries that follow the SI system (Australia, UK, most of Europe) require energy to be listed in kilojoules on food labels. The United States primarily uses kilocalories (Calories). To convert a food label kJ value to kcal, divide by 4.184.

Kilojoules to Calories Converter

Enter a value in kilojoules and instantly get the equivalent in thermochemical calories (1 kJ = 239.006 cal).

Kilojoules to Calories

Energy in Kilojoules (kJ)

Calories (cal)

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1 kJ ≈ 239.006 cal (thermochemical)

Quick Reference Table

Common kilojoule values converted to thermochemical calories

Kilojoules (kJ)	Calories (cal)

1 kJ = 1,000 J ÷ 4.184 = 239.006 cal (thermochemical definition, IUPAC)

Summary

Enter a value in kilojoules and instantly get the equivalent in thermochemical calories (1 kJ = 239.006 cal).

How it works

Type a value in kilojoules into the input field.
The converter multiplies your value by 1,000 to get joules, then divides by 4.184.
Results appear instantly — no button click needed.
Click "Copy" to copy the calorie result to your clipboard.
Scroll down to the reference table for common kJ-to-cal pairs.

Use cases

Convert thermochemical energy values from kilojoules (kJ) to small calories (cal).
Check chemistry or physics homework answers in kilojoules against calorie equivalents.
Cross-reference calorimeter results between SI (kJ) and thermochemical (cal) units.
Convert reaction enthalpies or heat capacities between kilojoules and gram calories.
Quickly look up standard kJ-to-cal conversions for laboratory reports and thermodynamic calculations.

Frequently Asked Questions

Last updated: 2026-09-19 · Reviewed by Nham Vu