How many calories are in one joule?

One joule equals approximately 0.239006 thermochemical calories (cal). Equivalently, 1 cal = 4.184 J by definition, so 1 J = 1/4.184 cal.

What type of calorie does this tool use?

This tool uses the thermochemical calorie (cal_th), defined as exactly 4.184 joules. It is the most common calorie in chemistry and physics. It is NOT the food calorie (kilocalorie, kcal), which is 1,000 times larger.

How do I convert kilojoules (kJ) to calories?

Multiply your kJ value by 1,000 to get joules, then divide by 4.184. For example, 1 kJ = 1,000 J / 4.184 ≈ 239.006 cal. For food energy, divide kJ by 4.184 to get kcal directly.

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 contexts.

What is the difference between a calorie and a food Calorie?

A small calorie (cal) is the energy needed to raise 1 gram of water by 1 °C (= 4.184 J). A food Calorie (written with a capital C) is actually a kilocalorie (kcal) and equals 1,000 cal or 4,184 J. This tool works with small calories only.

Joules to Calories Converter

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

Enter a value in joules and instantly get the equivalent in thermochemical calories (1 cal = 4.184 J).

Joules to Calories

Energy in Joules (J)

Calories (cal)

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1 cal = 4.184 J (thermochemical, exact)

Quick Reference Table

Common joule values converted to thermochemical calories

Joules (J)	Calories (cal)

1 cal = 4.184 J (thermochemical definition, IUPAC)

Summary

Enter a value in joules and instantly get the equivalent in thermochemical calories (1 cal = 4.184 J).

How it works

Type a value in joules into the input field.
The converter divides your value by 4.184 to get thermochemical calories.
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 joule-to-calorie pairs.

Use cases

Convert physics or chemistry homework answers from joules to calories.
Check calorimeter results against calorie equivalents.
Cross-reference energy output figures between SI (joule) and older (calorie) units.
Verify exercise-energy data reported in joules against caloric values.
Quickly look up standard joule-to-calorie conversions for lab reports.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu