Convert Kilojoule to Kilocalorie
1 kilojoule = 0.2390057 kilocalorie (kcal). For example, 10 kilojoule = 2.390057 kilocalorie and 100 kilojoule = 23.90057 kilocalorie. Type any value below to convert kilojoule to kilocalorie both ways — it runs entirely in your browser.
Quick answer: Kilojoule to Kilocalorie
1 Kilojoule = 0.2390057 Kilocalorie (kJ → kcal). To convert kilojoule to kilocalorie, multiply by 0.2390057. To convert kilocalorie to kilojoule, multiply by 4.184. The converter at the top does this instantly and both ways; the sections below give the formula, worked examples, a full conversion chart and answers to the most common kilojoule-to-kilocalorie questions.
How to convert Kilojoule to Kilocalorie
To convert kilojoule to kilocalorie, multiply the number of kilojoule by the conversion factor 0.2390057, because 1 kJ = 0.2390057 kcal. The conversion is linear, so the same factor works for any value — whole numbers, decimals or fractions. For the reverse direction, 1 kcal = 4.184 kJ, so you divide by 0.2390057 (or multiply by 4.184) to turn kilocalorie back into kilojoule.
kcal = kJ × 0.2390057 ·
kJ = kcal × 4.184
- Write down the value you want to convert, in kilojoule.
- Multiply it by 0.2390057.
- The result is the same area/length/quantity expressed in kilocalorie.
Kilojoule to Kilocalorie — worked examples
Each row shows the exact arithmetic so you can follow the conversion step by step. For example, 5 kilojoule is 1.195029 kilocalorie because 5 kJ × 0.2390057 = 1.195029 kcal.
| Kilojoule | Calculation | Kilocalorie |
|---|---|---|
| 1 kJ | 1 kJ × 0.2390057 = 0.2390057 kcal | 0.2390057 kcal |
| 2 kJ | 2 kJ × 0.2390057 = 0.4780115 kcal | 0.4780115 kcal |
| 3 kJ | 3 kJ × 0.2390057 = 0.7170172 kcal | 0.7170172 kcal |
| 5 kJ | 5 kJ × 0.2390057 = 1.195029 kcal | 1.195029 kcal |
| 7 kJ | 7 kJ × 0.2390057 = 1.67304 kcal | 1.67304 kcal |
| 10 kJ | 10 kJ × 0.2390057 = 2.390057 kcal | 2.390057 kcal |
| 12 kJ | 12 kJ × 0.2390057 = 2.868069 kcal | 2.868069 kcal |
| 15 kJ | 15 kJ × 0.2390057 = 3.585086 kcal | 3.585086 kcal |
| 20 kJ | 20 kJ × 0.2390057 = 4.780115 kcal | 4.780115 kcal |
| 25 kJ | 25 kJ × 0.2390057 = 5.975143 kcal | 5.975143 kcal |
| 50 kJ | 50 kJ × 0.2390057 = 11.95029 kcal | 11.95029 kcal |
| 100 kJ | 100 kJ × 0.2390057 = 23.90057 kcal | 23.90057 kcal |
Common Kilojoule to Kilocalorie conversions
These are the kilojoule-to-kilocalorie values people look up most often. Every figure is computed from the exact factor, so you can rely on them for quick reference:
- 1 kilojoule = 0.2390057 kilocalorie
- 2 kilojoule = 0.4780115 kilocalorie
- 2.5 kilojoule = 0.5975143 kilocalorie
- 3 kilojoule = 0.7170172 kilocalorie
- 4 kilojoule = 0.9560229 kilocalorie
- 5 kilojoule = 1.195029 kilocalorie
- 6 kilojoule = 1.434034 kilocalorie
- 7 kilojoule = 1.67304 kilocalorie
- 8 kilojoule = 1.912046 kilocalorie
- 9 kilojoule = 2.151052 kilocalorie
- 10 kilojoule = 2.390057 kilocalorie
- 12 kilojoule = 2.868069 kilocalorie
- 15 kilojoule = 3.585086 kilocalorie
- 20 kilojoule = 4.780115 kilocalorie
- 25 kilojoule = 5.975143 kilocalorie
- 30 kilojoule = 7.170172 kilocalorie
- 50 kilojoule = 11.95029 kilocalorie
- 75 kilojoule = 17.92543 kilocalorie
- 100 kilojoule = 23.90057 kilocalorie
- 200 kilojoule = 47.80115 kilocalorie
- 500 kilojoule = 119.5029 kilocalorie
- 1000 kilojoule = 239.0057 kilocalorie
Kilojoule to Kilocalorie conversion chart (both directions)
The chart below converts kilojoule to kilocalorie and kilocalorie to kilojoule side by side, so it works whichever way you need. 1 kilojoule = 0.2390057 kilocalorie, and 1 kilocalorie = 4.184 kilojoule.
| Kilojoule → Kilocalorie | Kilocalorie → Kilojoule |
|---|---|
| 0.25 kJ = 0.05975143 kcal | 0.25 kcal = 1.046 kJ |
| 0.5 kJ = 0.1195029 kcal | 0.5 kcal = 2.092 kJ |
| 1 kJ = 0.2390057 kcal | 1 kcal = 4.184 kJ |
| 2 kJ = 0.4780115 kcal | 2 kcal = 8.368 kJ |
| 3 kJ = 0.7170172 kcal | 3 kcal = 12.552 kJ |
| 4 kJ = 0.9560229 kcal | 4 kcal = 16.736 kJ |
| 5 kJ = 1.195029 kcal | 5 kcal = 20.92 kJ |
| 6 kJ = 1.434034 kcal | 6 kcal = 25.104 kJ |
| 7 kJ = 1.67304 kcal | 7 kcal = 29.288 kJ |
| 8 kJ = 1.912046 kcal | 8 kcal = 33.472 kJ |
| 9 kJ = 2.151052 kcal | 9 kcal = 37.656 kJ |
| 10 kJ = 2.390057 kcal | 10 kcal = 41.84 kJ |
| 12 kJ = 2.868069 kcal | 12 kcal = 50.208 kJ |
| 15 kJ = 3.585086 kcal | 15 kcal = 62.76 kJ |
| 20 kJ = 4.780115 kcal | 20 kcal = 83.68 kJ |
| 25 kJ = 5.975143 kcal | 25 kcal = 104.6 kJ |
| 30 kJ = 7.170172 kcal | 30 kcal = 125.52 kJ |
| 40 kJ = 9.560229 kcal | 40 kcal = 167.36 kJ |
| 50 kJ = 11.95029 kcal | 50 kcal = 209.2 kJ |
| 75 kJ = 17.92543 kcal | 75 kcal = 313.8 kJ |
| 100 kJ = 23.90057 kcal | 100 kcal = 418.4 kJ |
| 150 kJ = 35.85086 kcal | 150 kcal = 627.6 kJ |
| 200 kJ = 47.80115 kcal | 200 kcal = 836.8 kJ |
| 250 kJ = 59.75143 kcal | 250 kcal = 1,046 kJ |
| 500 kJ = 119.5029 kcal | 500 kcal = 2,092 kJ |
| 1000 kJ = 239.0057 kcal | 1000 kcal = 4,184 kJ |
Kilojoule vs Kilocalorie: which is bigger?
A kilocalorie is the larger unit: one kilocalorie equals 4.184 kilojoules. Put another way, you need 4.184 kilojoules to make a single kilocalorie.
What is a Kilojoule? History, origin and usage
The kilojoule is simply 1,000 joules, formed with the SI “kilo” prefix, and it inherits the joule’s heritage from James Prescott Joule’s heat experiments. It became the practical everyday multiple of the joule because single joules are inconveniently small for food, fuel and exercise energy.
The kilojoule is the energy figure on nutrition labels across Europe, Australia and many other countries, usually printed alongside (or instead of) kilocalories. It is also handy for stating the energy of small chemical reactions, batteries and household tasks.
Australia and New Zealand use kilojoules almost exclusively for food energy, so a chocolate bar there is rated in kJ rather than Calories. One food “Calorie” (a kilocalorie) is about 4.184 kJ, which is why kilojoule figures on labels look roughly four times larger than the familiar calorie counts.
What is a Kilocalorie? History, origin and usage
The kilocalorie is 1,000 small calories, and it is the unit behind the familiar food “Calorie” (often written with a capital C). It descends from the calorimetry of Nicolas Clément and the 19th-century nutrition science of Marcellin Berthelot and Wilbur Atwater, who needed a human-scale unit for the energy in food.
The kilocalorie is the energy figure on nutrition labels in the United States and many other countries, where it is simply called the “calorie.” Dietitians, food scientists and fitness apps use kcal to track energy intake and expenditure.
When a label says a food has “250 calories,” it means 250 kilocalories — 250,000 of the physicists’ small calories. The macronutrients differ in energy density: fat supplies about 9 kcal per gram, while carbohydrate and protein each supply about 4 kcal per gram.
Convert 1 Kilojoule to other units
It can help to see a kilojoule next to the other units it is commonly compared with. One kilojoule (kJ) is equal to:
| 1 Kilojoule equals | Unit |
|---|---|
| 1,000 J | Joule |
| 1,000 N·m | Newton-metre |
| 0.001 MJ | Megajoule |
| 0.2777778 Wh | Watt-hour |
| 0.0002777778 kWh | Kilowatt-hour |
| 0.0000002777778 MWh | Megawatt-hour |
| 737.5621 ft·lbf | Foot-pound |
| 6,241,509,000,000,000 MeV | Megaelectronvolt |
| 239.0057 cal | Calorie |
| 0.2390057 kcal | Kilocalorie |
| 0.9478171 BTU | British Thermal Unit |
Convert 1 Kilocalorie to other units
One kilocalorie (kcal) is equal to:
| 1 Kilocalorie equals | Unit |
|---|---|
| 4,184 J | Joule |
| 4,184 N·m | Newton-metre |
| 4.184 kJ | Kilojoule |
| 0.004184 MJ | Megajoule |
| 1.162222 Wh | Watt-hour |
| 0.001162222 kWh | Kilowatt-hour |
| 0.000001162222 MWh | Megawatt-hour |
| 3,085.96 ft·lbf | Foot-pound |
| 26,114,470,000,000,000 MeV | Megaelectronvolt |
| 1,000 cal | Calorie |
| 3.965667 BTU | British Thermal Unit |
Tips for converting Kilojoule to Kilocalorie
- To go from kilojoule to kilocalorie, multiply by 0.2390057; to go back, divide by 0.2390057 (or multiply by 4.184).
- For a quick mental estimate, remember that 1 kilojoule ≈ 0.2390057 kilocalorie, so 10 kilojoule ≈ 2.390057 kilocalorie.
- The converter above keeps full precision; the tables round for readability, so use the tool for exact figures.
- Both fields update live as you type — change either side to convert in that direction.
How to use this Kilojoule to Kilocalorie converter
Type a number into the Kilojoule field and the equivalent in Kilocalorie appears instantly — there is no “convert” button to press and nothing is sent to a server, so it works offline once the page has loaded and is safe for any data. You can also type into the Kilocalorie field to convert the other way (kilocalorie to kilojoule). Use the swap control to flip the two units, and copy the result with a single click. Because the calculation runs in your browser with full floating-point precision, the converter is more exact than the rounded figures shown in the reference chart above — use the chart for quick look-ups and the tool for precise work.
Accuracy and method
Every figure on this page — the formula, the worked examples, the conversion chart and the “convert to other units” tables — is computed from a single verified conversion factor (1 kJ = 0.2390057 kcal), never copied from a hand-typed lookup table that could drift. That factor is derived from each unit’s definition in terms of a common base unit, and an automated check re-verifies all of the site’s factors on every update, so the numbers here stay correct over time. This matters for kilojoule-to-kilocalorie conversions because a small rounding error in a published table compounds quickly at larger quantities; computing from the exact factor avoids that.
Sources
- BIPM — The International System of Units (SI Brochure) — the defining document for the SI, published by the International Bureau of Weights and Measures. It fixes the base unit that this conversion resolves to, which is why the factor here can be exact rather than approximate.
- NIST — Definitions of the SI base units — the US National Institute of Standards and Technology reference for the SI base units, used here as an independent cross-check on the base-unit definition.
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Frequently asked questions
- How many kilocalorie are in 1 kilojoule?
- 1 kilojoule = 0.2390057 kilocalorie (kcal). To convert any number of kilojoule to kilocalorie, multiply by 0.2390057.
- How do I convert kilojoule to kilocalorie?
- Multiply the number of kilojoule by 0.2390057. For example, 10 kilojoule = 10 × 0.2390057 = 2.390057 kilocalorie, and 25 kilojoule = 5.975143 kilocalorie.
- How many kilojoule are in 1 kilocalorie?
- 1 kilocalorie = 4.184 kilojoule. So to convert kilocalorie back to kilojoule, multiply by 4.184.
- What is the formula to convert kilojoule to kilocalorie?
- kilocalorie = kilojoule × 0.2390057. The reverse formula is kilojoule = kilocalorie × 4.184.
- How much is 100 kilojoule in kilocalorie?
- 100 kilojoule = 23.90057 kilocalorie. (And 1000 kilojoule = 239.0057 kilocalorie.)
- Which is bigger, a kilojoule or a kilocalorie?
- A kilocalorie is larger: 1 kilocalorie = 4.184 kilojoule.
- Is this kilojoule to kilocalorie converter accurate?
- Yes — every value is computed from the exact 0.2390057 kcal per kJ factor (not rounded look-up tables), and the factors are re-verified automatically on every update.
- Can I convert kilocalorie to kilojoule too?
- Yes. The converter works both ways — enter a value in either field. 1 kilocalorie = 4.184 kilojoule.