2 J to kcal — 2 joules in kilocalories
Exact 2 ÷ 4,184 = 0.000478011472
2 joules in other units
| Kilojoules | 0.002 | kJ |
|---|---|---|
| Megajoules | 0.000002 | MJ |
| Watt-hours | 0.000555555556 | Wh |
| Kilowatt-hours | 5.5556e-7 | kWh |
| Calories | 0.47801147 | cal |
| Kilocalories | 0.000478011472 | kcal |
| British thermal units | 0.001895634241 | BTU |
| Therms | 1.8956e-8 | thm |
| Foot-pounds | 1.475124 | ft·lbf |
| Electronvolts | 12,483,018,148,921,526,272 | eV |
J to kcal at a glance
| Joules | Kilocalories |
|---|---|
| 1 J | 0.000239005736 kcal |
| 2 J | 0.000478011472 kcal |
| 3 J | 0.000717017208 kcal |
| 5 J | 0.001195028681 kcal |
| 10 J | 0.002390057361 kcal |
| 20 J | 0.004780114723 kcal |
| 25 J | 0.005975143403 kcal |
| 50 J | 0.01195029 kcal |
| 100 J | 0.02390057 kcal |
| 250 J | 0.05975143 kcal |
| 500 J | 0.11950287 kcal |
| 1,000 J | 0.23900574 kcal |
How to convert joules to kilocalories
Multiply by 0.000239005736 — one joule is 0.000239005736 kilocalories. That factor is exact: it comes from the definition of the units rather than from a measurement, so it will not change and does not need rounding.
Working 2 ÷ 4,184 = 0.000478011472
What these units are
The joule and the kilocalorie are covered in the energy unit guide, along with every other unit on this page.
Questions
How many kilocalories are in a joule?
One joule is 0.000239005736 kilocalories. This figure is exact — it comes from the definition of the unit, not a measurement.
What is 2 joules in kilocalories?
2 joules is 0.000478011472 kilocalories. The working is 2 ÷ 4,184 = 0.000478011472.
Is a food Calorie the same as a calorie?
No — it is a thousand of them. The Calorie on a nutrition label is a kilocalorie, written with a capital C in principle and almost never in practice. A 250 Calorie chocolate bar holds 250,000 physics calories, or about 1,046 kilojoules, which is why European labels quote kJ alongside.
What does a kilowatt-hour actually represent?
One kilowatt drawn for one hour — a 1,000 W heater running for sixty minutes, or a 100 W bulb for ten hours. It is the unit your electricity bill is priced in, and it equals exactly 3.6 million joules.
How much energy is one BTU?
Roughly the heat needed to raise one pound of water by one degree Fahrenheit — about 1,055 joules, or the energy in a single kitchen match. Air conditioners are rated in BTU per hour, where a 12,000 BTU/h unit is one "ton" of cooling and draws around 3.5 kW of heat.
Why is the electronvolt so small?
Because it is sized for single particles: it is the energy one electron picks up crossing a one-volt potential difference. At about 1.6 × 10⁻¹⁹ joules it would be absurd for anything larger, which is precisely why particle physics uses it instead of dragging around twenty leading zeros.