Does my data get uploaded anywhere?
No. Everything runs locally in your browser and nothing is sent to a server.
Is this free to use?
Yes. It is completely free, with no account, no signup, and no usage limits.
Does it work on a phone?
Yes. The page runs in any modern mobile browser, on iPhone and Android alike, with no app to install.
Is a food Calorie the same as a calorie?
No. The Calorie with a capital C on a nutrition label is a kilocalorie, which is 1,000 small calories, or 4,184 J. So a 2,000 Calorie diet is 2,000 kcal, which is 8,368 kJ, and entering 2,000 kcal here gives you exactly that.
How many joules are in a kilowatt hour?
3,600,000 J, because a kilowatt is 1,000 J per second and an hour is 3,600 seconds. In other units, 1 kWh is 3.6 MJ, 860.42 kcal, or 3412.14 BTU.
Which calorie definition does this converter use?
The thermochemical calorie, exactly 4.184 J, which is the definition used in nutrition and in most chemistry. Other definitions exist (the 15 degree calorie and the IT calorie) but they differ by less than 0.07%, well below the precision of any food label.
How much energy does a 60 W bulb use if it is left on all day?
60 W for 24 hours is 1.44 kWh, which is 5,184,000 J or 1,239 kcal. The converter handles the unit change but not the multiplication by time, so work out the watt-hours first and then convert.
How do I convert kcal to kJ for a nutrition label?
Multiply by 4.184. European labels print both, so 250 kcal appears as 1046 kJ. Enter the kcal figure, select Kilojoule, and the tool does the same arithmetic exactly.