1 cal = 0.001 kcal (calorie → kilocalorie)
1 cal = 0.001 kcal
1 calorie equals 0.001 kilocalories. To convert calories to kilocalories, multiply the calorie value by 0.001. For quick reference: 1 cal = 0.001 kcal, 5 cal = 0.005 kcal, 10 cal = 0.01 kcal, 100 cal = 0.1 kcal.
Kilocalories = Calories × 0.001Small calories to kilocalories divides by 1,000 — the kilocalorie is simply 1,000 thermochemical calories, each of 4.184 J. The arithmetic is trivial; the naming is the whole hazard. US food labels write 'Calories' (capital C) meaning kcal, physics texts write 'calories' meaning the small unit, and casual writing mixes both freely. A match burns about 1,000 small calories, which is just 1 kcal — a hundredth of a medium apple's 95 kcal. Always identify which calorie a source means before converting.
Thermochemistry textbooks sometimes report reaction energies in small calories per mole, a figure so large in raw calories that converting to kilocalories per mole is the only readable way to present it in a table. A reaction releasing 50,000 calories per mole is 50.00 kcal/mol, a typical bond-dissociation-energy scale. Because kilocalories per mole remains the standard unit in much of organic and biochemistry literature despite SI's preference for kJ/mol, this conversion bridges an older calorie-based dataset into the kcal/mol figures still printed in most chemistry reference tables.
Start with your value in calories.
Multiply the calorie value by 0.001. This is the exact conversion factor from calories to kilocalories.
The product is your value in kilocalories. For example, 5 cal × 0.001 = 0.005 kcal.
The exact factor from calories to kilocalories is 0.001.
Kilocalories = Calories × 0.001
Fifty common reference values, hand-picked for skim utility. Use the calculator above for any value not listed.
| Calories (cal) | Kilocalories (kcal) |
|---|---|
| 0.001 cal | 1.0000 × 10^−6 kcal |
| 0.01 cal | 1.0000 × 10^−5 kcal |
| 0.1 cal | 0.0001 kcal |
| 0.5 cal | 0.0005 kcal |
| 1 cal | 0.001 kcal |
| 1.5 cal | 0.0015 kcal |
| 2 cal | 0.002 kcal |
| 5 cal | 0.005 kcal |
| 10 cal | 0.01 kcal |
| 20 cal | 0.02 kcal |
| 50 cal | 0.05 kcal |
| 100 cal | 0.1 kcal |
| 200 cal | 0.2 kcal |
| 250 cal | 0.25 kcal |
| 500 cal | 0.5 kcal |
| 1000 cal | 1 kcal |
| 2000 cal | 2 kcal |
| 2500 cal | 2.5 kcal |
| 3600 cal | 3.6 kcal |
| 5000 cal | 5 kcal |
| 7500 cal | 7.5 kcal |
| 10000 cal | 10 kcal |
| 25000 cal | 25 kcal |
| 50000 cal | 50 kcal |
| 100000 cal | 100 kcal |
| 250000 cal | 250 kcal |
| 500000 cal | 500 kcal |
| 1000000 cal | 1000 kcal |
| 2000000 cal | 2000 kcal |
| 3600000 cal | 3600 kcal |
| 5000000 cal | 5000 kcal |
| 10000000 cal | 10000 kcal |
| 25000000 cal | 25000 kcal |
| 50000000 cal | 50000 kcal |
| 100000000 cal | 100000 kcal |
| 250000000 cal | 250000 kcal |
| 500000000 cal | 500000 kcal |
| 1000000000 cal | 1000000 kcal |
| 2000000000 cal | 2000000 kcal |
| 5000000000 cal | 5000000 kcal |
| 10000000000 cal | 10000000 kcal |
| 20000000000 cal | 20000000 kcal |
| 50000000000 cal | 50000000 kcal |
| 100000000000 cal | 100000000 kcal |
| 1000000000000 cal | 1000000000 kcal |
| 10000000000000 cal | 10000000000 kcal |
| 100000000000000 cal | 100000000000 kcal |
| 1000000000000000 cal | 1000000000000 kcal |
| 10000000000000000 cal | 10000000000000 kcal |
| 100000000000000000 cal | 100000000000000 kcal |
Burning a single dietary calorie of fat releases about 4.184 kJ of heat. A wooden match releases roughly 1,000 small calories.
Convertitive uses the thermochemical (small) calorie, defined as exactly 4.184 joules — the energy needed to raise 1 g of water by 1 °C. Do not confuse it with the large calorie (kcal) used on US nutrition labels, which is 1,000 of these small calories.
The kilocalorie (kcal) equals exactly 4,184 joules — 1,000 small calories. This is the 'Calorie' (capital C) printed on US nutrition labels: when a food package says '250 Calories', it means 250 kcal. Outside the US, food energy is usually labeled in kJ as well.
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