Last updated: September 16, 2026
Quick answer: Multiply food calories (kcal) by 4.184 to get kilojoules (kJ). 1 kcal = 4.184 kJ. So 100 kcal = 418.4 kJ, 500 kcal = 2,092 kJ, and a typical 2,000 kcal daily intake = 8,368 kJ. To go the other way, see our kJ to calories converter.
Kilocalorie to Kilojoule
Instantly convert kilocalorie to kilojoule with fast, accurate, real-time results.
Formula: calories to kilojoules
One food calorie (kilocalorie, kcal) equals exactly 4.184 kilojoules. This is the thermochemical calorie — the amount of energy needed to raise 1 kilogram of water by 1°C.
Examples:
- 95 kcal (medium apple) × 4.184 = 397.5 kJ
- 250 kcal (small meal) × 4.184 = 1,046 kJ
- 600 kcal (restaurant main) × 4.184 = 2,510 kJ
- 2,000 kcal (daily intake) × 4.184 = 8,368 kJ
Calories vs kcal — what's on food labels?
The term "calorie" is famously confusing because it's used in two ways:
- Food calorie (Cal, kcal): The "Calories" on nutrition labels in the US and UK are actually kilocalories (kcal). So "200 Calories" on a cereal box means 200 kcal = 836.8 kJ.
- Small calorie (cal): The scientific calorie — 1/1,000 of a food calorie. Rarely used outside physics and chemistry labs. 1 cal = 0.004184 kJ.
In Australia, New Zealand, most of Europe, and medical literature, food energy is expressed in kilojoules (kJ). A can of cola labeled "630 kJ" in Sydney is the same as "150 kcal" (Calories) in New York.
| Label says | Country / region | What it means | Equivalent |
|---|---|---|---|
| Calories or Cal (capital C) | US, Canada | kcal (food calories) | 1 Cal = 4.184 kJ |
| kcal | UK, EU, international | kilocalories | 1 kcal = 4.184 kJ |
| kJ | Australia, NZ, EU | kilojoules | 1 kJ = 0.239 kcal |
| cal (lowercase) | Science / lab use | small calories | 1,000 cal = 1 kcal |
Common foods in kcal and kJ
These values are approximate averages — actual energy content varies by brand, preparation method, and portion size. Values shown are per standard serving.
| Food / drink | Serving | kcal | kJ |
|---|---|---|---|
| Apple (medium) | 182 g | 95 kcal | 397 kJ |
| Banana (medium) | 118 g | 105 kcal | 439 kJ |
| Orange (medium) | 131 g | 62 kcal | 259 kJ |
| Boiled egg (large) | 50 g | 77 kcal | 322 kJ |
| White bread slice | 28 g | 75 kcal | 314 kJ |
| Cooked white rice (1 cup) | 186 g | 242 kcal | 1,013 kJ |
| Chicken breast (grilled) | 140 g | 231 kcal | 967 kJ |
| Salmon fillet (grilled) | 154 g | 280 kcal | 1,171 kJ |
| Whole milk (1 cup / 244 mL) | 244 mL | 149 kcal | 623 kJ |
| Cola (355 mL can) | 355 mL | 140 kcal | 586 kJ |
| Black coffee | 240 mL | 2 kcal | 8 kJ |
| Butter (1 tablespoon) | 14 g | 102 kcal | 427 kJ |
| Chocolate bar (milk, standard) | 44 g | 235 kcal | 983 kJ |
| Big Mac (McDonald's, approximate) | 220 g | 563 kcal | 2,355 kJ |
Daily energy intake reference
The World Health Organization (WHO) and most national dietary guidelines express recommended daily energy intake in both kcal and kJ:
| Group | Daily intake (kcal) | Daily intake (kJ) |
|---|---|---|
| Children 2–3 years | 1,000–1,400 kcal | 4,184–5,858 kJ |
| Children 4–8 years | 1,200–1,600 kcal | 5,021–6,694 kJ |
| Adolescents 9–13 years | 1,400–2,200 kcal | 5,858–9,205 kJ |
| Adult women (sedentary) | 1,600–2,000 kcal | 6,694–8,368 kJ |
| Adult women (active) | 2,000–2,400 kcal | 8,368–10,042 kJ |
| Adult men (sedentary) | 2,000–2,600 kcal | 8,368–10,878 kJ |
| Adult men (active) | 2,400–3,000 kcal | 10,042–12,552 kJ |
| Standard food label reference | 2,000 kcal | 8,368 kJ |
Exercise energy burn (kcal and kJ)
These estimates are for a 70 kg (154 lb) adult. Energy burn scales with body weight — a 90 kg person burns roughly 30% more.
| Activity | Duration | kcal burned | kJ burned |
|---|---|---|---|
| Walking (5 km/h) | 30 min | ~140 kcal | ~586 kJ |
| Jogging (8 km/h) | 30 min | ~280 kcal | ~1,171 kJ |
| Running (12 km/h) | 30 min | ~400 kcal | ~1,674 kJ |
| Cycling (moderate) | 30 min | ~240 kcal | ~1,004 kJ |
| Swimming (moderate) | 30 min | ~250 kcal | ~1,046 kJ |
| Weightlifting | 30 min | ~180 kcal | ~753 kJ |
| Yoga | 60 min | ~200 kcal | ~837 kJ |
| HIIT | 30 min | ~350 kcal | ~1,464 kJ |
Calories to kJ conversion table
| Calories (kcal) | Kilojoules (kJ) | Calories (kcal) | Kilojoules (kJ) |
|---|---|---|---|
| 50 kcal | 209.2 kJ | 600 kcal | 2,510.4 kJ |
| 100 kcal | 418.4 kJ | 700 kcal | 2,928.8 kJ |
| 150 kcal | 627.6 kJ | 800 kcal | 3,347.2 kJ |
| 200 kcal | 836.8 kJ | 900 kcal | 3,765.6 kJ |
| 250 kcal | 1,046.0 kJ | 1,000 kcal | 4,184.0 kJ |
| 300 kcal | 1,255.2 kJ | 1,200 kcal | 5,020.8 kJ |
| 350 kcal | 1,464.4 kJ | 1,500 kcal | 6,276.0 kJ |
| 400 kcal | 1,673.6 kJ | 1,800 kcal | 7,531.2 kJ |
| 450 kcal | 1,882.8 kJ | 2,000 kcal | 8,368.0 kJ |
| 500 kcal | 2,092.0 kJ | 2,500 kcal | 10,460.0 kJ |
| 550 kcal | 2,301.2 kJ | 3,000 kcal | 12,552.0 kJ |
Frequently asked questions
Is 1 calorie the same as 1 kcal?
On food labels, yes — "Calories" (with a capital C) always means kilocalories (kcal). Scientifically, 1 calorie (lowercase) = 0.001 kcal. So a 200-Calorie snack = 200 kcal = 836.8 kJ. To avoid confusion, most health professionals use "kcal" for food energy and reserve "calorie" for scientific contexts.
How many kJ is 2,000 calories?
2,000 kcal × 4.184 = 8,368 kJ. This is the reference daily intake used on nutrition labels in the US (2,000 Calories) and Australia/NZ (8,700 kJ, slightly rounded up). If your label says "based on a 8,700 kJ daily diet," that's approximately 2,079 kcal.
Why do Australian food labels show kJ but US labels show Calories?
It's a historical difference in measurement systems. Australia adopted SI units (metric, including joules) in 1974; the US retained the non-metric calorie convention. Both values represent the same energy — just measured in different units. A product with "630 kJ" in Australia has "150 Cal" in the US.
What is the difference between kJ and kcal?
Both measure energy. 1 kcal = 4.184 kJ exactly. "kJ" (kilojoule) is the SI unit of energy; "kcal" (kilocalorie) is the traditional dietary unit. Kilojoules are used by scientists and in metric countries; kilocalories dominate in the US, Canada, and UK nutrition labeling. Nutritionally, they're interchangeable — just different scales.
How do I convert kJ back to calories?
Divide kJ by 4.184 to get kcal (food calories). So 2,092 kJ ÷ 4.184 = 500 kcal. See our kJ to calories converter for the reverse calculation with a full table and food label examples.
How many kJ is 500 calories?
500 kcal × 4.184 = 2,092 kJ. This is roughly the energy in a standard restaurant starter or a small fast-food meal. It also represents about a 25% reduction from a 2,000 kcal/day reference diet — often cited in weight loss contexts as a daily deficit target.
Sources and references
- Food and Agriculture Organization (FAO) / WHO. Energy and protein requirements. WHO Technical Report Series, No. 724.
- U.S. Department of Agriculture (USDA). FoodData Central. National Agricultural Library.
- Food Standards Australia New Zealand (FSANZ). Energy calculation for food labels. FSANZ, 2020.
- Bureau International des Poids et Mesures (BIPM). The International System of Units (SI), 9th edition, 2019. (Definition of joule.)
- Ainsworth BE et al. 2011 Compendium of Physical Activities. Medicine & Science in Sports & Exercise, 2011.
Related converters
Author
Shakeel Muzaffar is the Founder and Editor-in-Chief of MultiCalculators.com, bringing over 15 years of experience in digital publishing, product strategy, and online tool development. He leads the platform's editorial vision, ensuring every calculator meets strict standards for accuracy, usability, and real-world value. Shakeel personally oversees content quality, formula verification workflows, and the platform's commitment to publishing tools that are genuinely useful for students, professionals, and everyday users worldwide.
