How many joules are in 1 kilocalorie?

Exactly 4,184 joules. This is the thermochemical definition: 1 kcal = 4,184 J = 4.184 kJ. Food labels in the US use "Calories" (capital C) which equals 1 kcal.

What is the difference between a calorie and a kilocalorie?

1 kilocalorie (kcal) = 1,000 small calories (cal). On nutrition labels the word "Calorie" (capital C) refers to a kilocalorie. 1 food Calorie = 4,184 J.

How do I convert kcal to kJ?

Multiply kcal by 4.184 to get kilojoules. For example, 100 kcal = 418.4 kJ. Many countries print both kcal and kJ on food packaging.

How many BTU is 1 kilocalorie?

Approximately 3.9657 BTU (British Thermal Units). The exact factor is 1 kcal = 3.96567 BTU (thermochemical).

What is a watt-hour in kilocalories?

1 watt-hour (Wh) = 3,600 J = 0.8604 kcal. So 1 kcal ≈ 1.163 Wh. Battery capacities sometimes express energy this way for comparison with dietary intake.

Kilocalories to Joules Converter

Name: Kilocalories to Joules Converter
Availability: InStock
Author: Nham Vu

Convert kilocalories to joules, kilojoules, calories, watt-hours, and BTU instantly — forward and reverse.

Kilocalories → Other Units

Enter a value in kcal to see all conversions.

Kilocalories (kcal)

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Results will appear here once you enter a value.

Joules → Kilocalories

Enter a value in joules for the reverse conversion.

Joules (J)

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Results will appear here once you enter a value.

Conversion Reference

From	To	Factor
1 kcal	Joules	4,184 J
1 kcal	Kilojoules	4.184 kJ
1 kcal	Calories (small)	1,000 cal
1 kcal	Watt-hours	1.162 Wh
1 kcal	BTU	3.966 BTU
1 J	Kilocalories	0.000239 kcal
1 kJ	Kilocalories	0.2390 kcal

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Summary

Convert kilocalories to joules, kilojoules, calories, watt-hours, and BTU instantly — forward and reverse.

How it works

Enter a kilocalorie (kcal) value in the top input field.
The tool multiplies by 4,184 to get joules (1 kcal = 4,184 J).
Results for kJ, cal, Wh, and BTU update instantly below.
Use the reverse section to convert from joules back to kcal.
Switch between common preset values using the quick-select buttons.

Use cases

Check the joule equivalent of a food calorie count on a nutrition label.
Convert dietary energy values between kcal and kJ for international recipes.
Calculate energy output in joules for physics or chemistry homework.
Compare workout energy expenditure in kcal versus watt-hours.
Convert heating values between BTU and kilocalories for engineering.
Verify thermochemistry calculations using SI and non-SI energy units.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu