Energy Converter

Convert between different energy units including joules, calories, kilowatt-hours, and more.

Energy Converter
ready
$ convert --from [unit] --to [unit] --value [number]
$
>
formulas.ts

// Common Energy Converter Formulas

1const1 kilojoule = 1000 joules
2const1 calorie ≈ 4.184 joules
3const1 kilowatt-hour = 3,600,000 joules
4const1 BTU ≈ 1,055.06 joules
references.json

// Common Energy Converter References

{
"Average Lightning Strike":"1 GJ",
"Daily Household Energy Use":"10-30 kWh",
"Smartphone Battery":"10-15 Wh",
"Daily Food Energy":"8400 kJ",
"Atomic Energy Level":"10⁻¹⁹ J",
"Sun's Energy Output":"3.8×10²⁶ W"
}
guide.md

Energy units across science and nutrition

Energy measures work or heat. The SI unit is the joule. Calories (nutrition and thermochemical) and kilowatt-hours appear in food labels and electricity bills. Those systems use different historical definitions, so stating which calorie you mean matters.

method.ts

Conversion path

  1. Convert inputs to joules.
  2. Map joules to calories, kilocalories, Wh, or kWh with published factors.
  3. Treat “Calorie” on food labels as kilocalorie (1 Cal = 1000 cal ≈ 4184 J).
sources.md

Sources

  • - SI Brochure: joule as SI derived unit of energy.
  • - NIST: thermochemical calorie ≈ 4.184 J; international steam table calorie differs slightly.
  • - 1 kWh = 3.6 × 10^6 J exactly (by definition of watt and hour).
examples.md

Worked examples

Snack label: 250 kcal to kJ

  1. Using 1 kcal = 4.184 kJ.
  2. 250 × 4.184 = 1046 kJ.

Result: 250 kcal = 1046 kJ

Electricity: 1.5 kWh to joules

  1. 1 kWh = 3,600,000 J.
  2. 1.5 × 3,600,000 = 5,400,000 J.

Result: 1.5 kWh = 5.4 MJ

Ambiguities

  • • Food “Calories” are kilocalories; lowercase “cal” in physics is 1000× smaller.
  • • BTU has several historical definitions; engineering contexts should specify which BTU.
  • • Electronvolts belong to particle physics and are tiny compared with joules.

Uses

  • - Reading nutrition labels that show both kcal and kJ.
  • - Estimating appliance energy use from kWh.
  • - Physics homework converting between joules and calories.
FAQ.md

Energy FAQ

01 Q: Is a joule the same as a watt-second?

Yes. 1 J = 1 W·s by definition.

02 Q: How many joules in a kilocalorie?

About 4184 J when using the thermochemical calorie convention common in nutrition.