OmniConvert
Energy • NIST Exact

Calories → Joules

cal → J

1 cal = 4.184 J• NIST Exact

cal → J Reference Table

cal J
0.01 cal 0.04184 J
0.1 cal 0.4184 J
0.5 cal 2.092 J
1 cal 4.184 J
2 cal 8.368 J
5 cal 20.92 J
10 cal 41.84 J
20 cal 83.68 J
50 cal 209.2 J
100 cal 418.4 J
500 cal 2092 J
1000 cal 4184 J

Values based on NIST SP 811 conversion factors

🌍 Real-World Examples

One thermochemical calorie

1 cal = 4.184 J

One food Calorie (kilocalorie)

1000 cal = 4184 J

Heating 500 g of water by 1°C

500 cal = 2092 J

Energy in a small snack (0.25 kcal)

250 cal = 1046 J

Why Convert Calories to Joules?

Converting between calories (cal) and joules (J) is one of the most common energy conversions. Whether for engineering, cooking, travel, or science, knowing how to quickly convert cal to J saves time and prevents errors.

Energy conversions between cal and J are important for nutrition, electricity costs, and engineering. Food labels in different countries use different energy units — China and the EU use kilojoules (kJ), while the US and Australia use Calories (kcal). Understanding kWh-to-joule conversions helps calculate electricity costs and compare energy efficiency of appliances. In HVAC, BTU ratings are standard in North America while watts or kilowatts are used elsewhere.

How to Convert Calories to Joules

To convert calories to joules, use the following formula:

J = cal × 4.184

Example: 1 cal = 4.184 J

For example, 5 cal = 20.92 J, 10 cal = 41.84 J, and 100 cal = 418.4 J. Our calculator above performs this conversion instantly with full precision — no rounding errors.

Common Use Cases

  • One thermochemical calorie: 1 cal = 4.184 J
  • One food Calorie (kilocalorie): 1000 cal = 4184 J
  • Heating 500 g of water by 1°C: 500 cal = 2092 J
  • Energy in a small snack (0.25 kcal): 250 cal = 1046 J

Common Mistakes to Avoid

  • Calorie vs kilocalorie: Food labels in the US show "Calories" (capital C) which are actually kilocalories (kcal). 1 food Calorie = 1 kcal = 4.184 kJ.
  • kWh is not kW: Kilowatt-hours (kWh) measure energy consumed over time, while kilowatts (kW) measure instantaneous power. Don't confuse them.
  • Regional food labels: China/EU labels use kilojoules (kJ), US/Australia use Calories (kcal). Check which system before comparing.

Pro Tips

  • Memorize the factor: 1 cal = 4.184 J. For quick mental math, remember this base conversion.
  • Quick reference: 5 cal = 20.92 J · 10 cal = 41.84 J · 25 cal = 104.6 J · 50 cal = 209.2 J · 100 cal = 418.4 J
  • Bookmark this page: Save this converter for instant access. It works offline once loaded — no internet needed.

Calories to Joules Conversion Table

calJ
0.01 cal0.04184 J
0.1 cal0.4184 J
0.5 cal2.092 J
1 cal4.184 J
2 cal8.368 J
5 cal20.92 J
10 cal41.84 J
20 cal83.68 J
50 cal209.2 J
100 cal418.4 J
500 cal2092 J
1000 cal4184 J

All values in this table are mathematically exact per NIST SP 811.

Frequently Asked Questions

How many joules are in 1 calorie?

1 cal equals 4.184 J. This is an exact conversion factor defined by NIST.

How do I convert calories to joules?

Multiply the value in cal by the conversion factor. For example, 10 cal = 41.84 J. Use our calculator above for instant results.

Is the calories to joules conversion exact?

Yes, this conversion is mathematically exact based on the international definition of these units (NIST SP 811).

Energy More Conversions

kJ → kcal kcal → kJ J → cal kWh → J BTU → J