Result
This page has no server side at all. The table you paste is parsed by JavaScript inside your own browser, the chart is drawn on a canvas element on your machine, and the export file is assembled locally. Nothing is uploaded, stored or written to any log. You can disconnect from the network after the page has loaded and everything will still work — which is the simplest way to verify the claim yourself.
Facts and limits of this method
| Base unit | Joule — all other units convert through it |
|---|---|
| 1 kWh | 3,600,000 J (3.6 MJ) — used on electricity bills |
| 1 kilocalorie | 4184 J — used for food energy content |
| 1 BTU | ≈1055.056 J (British thermal unit) |
| Total units | 9 — Wh, kWh, MWh, J, kJ, MJ, cal, kcal, BTU |
When it misleads you
- The calculation happens in two steps: the value is first converted to joules, then from joules to the target unit, so choosing the same unit for "from" and "to" leaves the result unchanged.
- The "calorie" in this converter is the thermochemical calorie (4.184 J), not the older 15° calorie or international steam calorie — in practice these definitions differ by less than 0.1%, negligible for everyday use.
- The food "Calorie" on nutrition labels actually means a kilocalorie (1000 calories) — when converting a food's energy content, use the "kilocalories" unit, not "calories".
- Rounding is applied only to the displayed result — internal calculations use the full precision of JavaScript floating-point numbers.
How it is calculated
Each of the nine units has a preset conversion factor to joules — for example, 1 kWh = 3,600,000 J, 1 BTU ≈ 1055.056 J.
The entered value is multiplied by the factor of the selected "from" unit, giving energy in joules.
The energy in joules is divided by the factor of the "to" unit, giving the result in the target unit.
The result is rounded to the chosen number of decimal places and updates instantly whenever the value, units or precision change.
Questions and answers
Why do electricity bills use kilowatt-hours instead of joules?
A kilowatt-hour is a more convenient everyday unit (its magnitude matches typical daily consumption), while the same amounts in joules would be much larger numbers (1 kWh = 3,600,000 J).
Is the "Calorie" on a food label a calorie or a kilocalorie?
On most nutrition labels, "Calorie" (capitalized) actually means a kilocalorie — a historical simplification in the food industry; for an exact conversion, use the "kilocalories" unit.
Where is BTU used?
The British thermal unit is common in the US for stating the power and energy consumption of heating, ventilation and air conditioning (HVAC) systems.
Is my data sent anywhere?
No, the whole calculation runs in your browser.