Calories ↔ Joules Converter
Convert between calories and joules instantly
Calorie Type:
cal
Cal (kcal)
⇄
SI unit of energy
Conversion Result
100 cal = 418.4 J
1 cal = 4.184 J • 1 Cal = 4184 J
📚 Calories ↔ Joules Conversion Details
⚠️ Important: There are two types of calories used in different contexts:
- Small calorie (cal): The amount of energy needed to raise 1 gram of water by 1°C
- Large calorie (Cal or kcal): Also called "food calorie" = 1000 small calories
Calories to Joules Formula
joules = calories × 4.184
To convert calories to joules, multiply calories by 4.184.
Joules to Calories Formula
calories = joules ÷ 4.184
To convert joules to calories, divide joules by 4.184.
Calorie Types
- Small calorie (cal): 1 cal = 4.184 J
- Large calorie (Cal/kcal): 1 Cal = 4184 J
- Food labels use large calories (Cal)
- Scientific work uses small calories (cal)
Common Uses
- Nutrition and food energy
- Physics and engineering
- Chemistry experiments
- Exercise energy expenditure
⚡ How This Converter Works
This is a bidirectional converter that works in real-time:
- Select calorie type: Choose between small calories (cal) or food calories (Cal/kcal)
- Calories → Joules: When you type in the calories field, joules update automatically
- Joules → Calories: When you type in the joules field, calories update automatically
- No swapping needed: Both conversions happen simultaneously
// Conversion Formulas:
// For small calories (cal):
J = cal × 4.184
cal = J ÷ 4.184
// For food calories (Cal/kcal):
J = Cal × 4184
Cal = J ÷ 4184
// Example 1: 100 small calories
J = 100 × 4.184 = 418.4 J
// Example 2: 1 food calorie (Cal)
J = 1 × 4184 = 4184 J
// For small calories (cal):
J = cal × 4.184
cal = J ÷ 4.184
// For food calories (Cal/kcal):
J = Cal × 4184
Cal = J ÷ 4184
// Example 1: 100 small calories
J = 100 × 4.184 = 418.4 J
// Example 2: 1 food calorie (Cal)
J = 1 × 4184 = 4184 J
⚠️ Common Confusion: Food labels in most countries (except the US) show energy in both kilojoules (kJ) and kilocalories (kcal). 1 kcal (food calorie) = 4.184 kJ.
📊 Conversion Table
| Calories (cal) | Joules (J) | Food Calories (Cal/kcal) | Kilojoules (kJ) |
|---|---|---|---|
| 1 cal | 4.184 J | 0.001 Cal | 0.004184 kJ |
| 10 cal | 41.84 J | 0.01 Cal | 0.04184 kJ |
| 100 cal | 418.4 J | 0.1 Cal | 0.4184 kJ |
| 1000 cal | 4184 J | 1 Cal (kcal) | 4.184 kJ |
| 2000 cal | 8368 J | 2 Cal | 8.368 kJ |
| 5000 cal | 20920 J | 5 Cal | 20.92 kJ |
❓ Frequently Asked Questions
Q: What's the difference between cal and Cal?
A: "cal" (small calorie) is the energy to heat 1g of water by 1°C. "Cal" (capital C, large calorie or food calorie) equals 1000 small calories (1 kcal).
Q: How many joules are in one calorie?
A: Exactly 4.184 joules in one small calorie (cal). Food calories (Cal/kcal) contain 4184 joules.
Q: Why are there two types of calories?
A: Small calories are used in chemistry and physics. Large calories (food calories) are used in nutrition because food contains much more energy.
Q: How accurate is this converter?
A: Uses the exact conversion factor of 4.184 joules per small calorie. Accurate to 4 decimal places.