// conversions › 1 · Basic Converters
Convert energy between joules, calories, watt-hours, BTU and electronvolts via the joule.
result = value × (from→J) ÷ (to→J)
It converts convert energy between joules, calories, watt-hours, btu and electronvolts via the joule by first normalising your value to the SI base unit (joule) and then scaling to your chosen target unit. This hub-and-spoke approach guarantees every unit pair is internally consistent.
1 kWh to MJ: 1 × 3.6e6 = 3.6e6 J, then ÷ 1e6 = 3.6 MJ.
Energy is one physical quantity, but fields invented their own units: joules in physics, calories in chemistry and food, watt-hours and kWh in electricity, BTU in heating. They all convert through the joule. Note the food "Calorie" is actually a kilocalorie (4184 J).
Nutrition (kcal), utility bills (kWh), HVAC (BTU) and physics (eV).
Conversions are exact ratios where the units are defined exactly (most SI and imperial units) and best-available constants otherwise. Extremely large or small magnitudes are shown in general (g) format; round-tripping through the base unit may introduce tiny floating-point differences in the final decimal places.