Enecon - Energy Unit Converter
Enecon is an energy unit converter. Type a number, pick the unit you have and the unit you want, and the answer updates as you type. It covers fourteen units that turn up in very different places: calories on a food label, BTU on an air conditioner, kilowatt-hours on an electricity bill, joules in a physics textbook and electron volts in particle physics.
Because those units span more than thirty orders of magnitude, Enecon switches to scientific notation for very small or very large results. Each unit also comes with a one-line explanation, which helps when you are not sure whether a recipe's 'Calorie' is the same as a lab's 'calorie' (it is not).
A Calculator tab adds four small tools: calories burned during exercise, a food energy adder, an appliance electricity estimate and an efficiency savings calculator.
The app runs entirely in your browser. What you enter is saved only on this device.
How to use Enecon
- Enter a value. On the Convert tab, type a number in the input field. It starts at 100 kcal converted to joules, and the result recalculates on every keystroke.
- Choose From and To units. Open the two unit menus and pick the starting unit and the target unit. The input field shows the symbol of the starting unit so you can see what you typed.
- Swap the direction. Tap the swap button between the two menus to reverse the conversion, for example to go from joules back to kcal.
- Narrow the list by category. Tap the filter icon in the top bar to show a Category menu, then choose Heat, Work/Energy, Power or Food/Nutrition. The unit menus then list only that group. Choose All to see every unit again.
- Read the details. Below the result, the Details card describes both units and, when calories are involved, notes that one food Calorie equals one kilocalorie. A Common Conversions card lists handy reference values.
- Look up a unit. Switch to the Unit Information tab to see every unit with its category, a short description and its size in joules.
- Try the calculators. Open the Calculator tab at the bottom and pick Exercise, Food, Appliances or Efficiency. Each one updates its total as you change the inputs.
Features
- Fourteen units: calorie, kilocalorie, food Calorie, BTU, joule, kilojoule, megajoule, erg, electron volt, keV, MeV, watt-hour, kilowatt-hour and megawatt-hour
- Live conversion as you type, with a one-tap swap button
- Automatic scientific notation for results below 0.001 or above ten million
- Optional category filter for heat, work/energy, power and food units
- Unit Information list showing each unit's value in joules
- Exercise calculator based on MET values, weight and duration
- Food energy adder with fifteen common foods and editable portions
- Appliance calculator for daily kWh with an estimated cost
- Efficiency calculator for output/input ratio and energy savings
- Converter screens available in many languages
Understanding energy units
Everything comes back to the joule
The joule (J) is the SI unit of energy: the work done by a force of one newton over one metre. Every other unit in Enecon is defined as a fixed number of joules, which is exactly how the converter works. It multiplies your value by the starting unit's size in joules, then divides by the target unit's size. That is why the Unit Information tab lists '1 unit = x J' for each entry.
Kilojoules and megajoules are simply 1,000 and 1,000,000 joules. The erg, from the older centimetre-gram-second system, is one ten-millionth of a joule.
Calorie, kilocalorie and the capital-C Calorie
A small calorie (cal) is roughly the heat needed to warm one gram of water by one degree Celsius; Enecon uses the thermochemical value of 4.184 J. A kilocalorie (kcal) is 1,000 of those, or 4,184 J. Food labels in many countries print 'Calories' with a capital C, and that food Calorie is the same as one kilocalorie. So a snack listed at 200 Calories contains about 837 kJ, which is the figure you will see on labels that use kilojoules, such as in Australia and the EU.
Mixing up cal and kcal is the most common energy-unit mistake, and it is off by a factor of a thousand.
BTU and heating or cooling
The British thermal unit is the heat needed to raise one pound of water by one degree Fahrenheit, about 1,055 J. In North America, air conditioners and heaters are often rated in BTU per hour, which is really a rate of energy use, i.e. power. Dividing a BTU/h rating by about 3.412 gives the equivalent in watts, so a 12,000 BTU/h unit moves heat at roughly 3.5 kW.
Watt-hours and your electricity bill
A watt is one joule per second, so a watt-hour is 3,600 J and a kilowatt-hour is 3.6 MJ. Utilities bill in kWh because it is a convenient size: a 1,000 W heater running for one hour uses 1 kWh. To estimate an appliance's use, multiply its wattage by its running hours and divide by 1,000. Fridges and other appliances that cycle on and off usually use less than this suggests.
Electron volts for very small energies
One electron volt (eV) is the energy an electron gains crossing a potential difference of one volt: about 1.602 x 10^-19 J. It is the natural scale for atoms and light; visible light photons carry roughly 1.6 to 3.3 eV, while particle accelerators work in MeV and beyond.
Estimating exercise energy with METs
A MET (metabolic equivalent of task) compares an activity with resting. A widely used estimate is kcal per minute = MET x 3.5 x body weight in kg / 200. For a 70 kg person doing a 5 MET activity for 30 minutes, that gives about 184 kcal. These are rough population averages; individual results vary with fitness, efficiency and how hard you really work.
Frequently asked questions
Where is my data stored?
Enecon does not ask for an account and does not send your numbers anywhere. Conversions and calculator inputs are worked out in your browser and nothing is saved, so the page starts fresh each time you open it.
Is a food Calorie the same as a kilocalorie?
Yes. The capital-C Calorie printed on food labels equals 1 kcal, or 1,000 small calories. Enecon lists it separately as 'Cal' so you can convert directly from a label.
Why does a result look like 1.6022x10^-19?
When a result is smaller than 0.001 or larger than ten million, Enecon shows it in scientific notation with up to four decimal places, so very large or small numbers stay readable. Other results are shown with up to six decimal places, without trailing zeros.
Which calorie value does Enecon use?
It uses the thermochemical calorie, 4.184 J, and 1,055.06 J for the BTU. Other definitions exist, such as the international table calorie at 4.1868 J, so other tools may differ slightly in the later digits.
How accurate are the exercise and food calculators?
They are rough guides. The exercise result uses your weight, a MET value for the chosen activity level and the duration; gender, height and age are collected on the form but do not change the result. Food values are typical figures per 100 g or per egg and vary between products.
How is the web version different from the phone app?
The converter and the calculators work the same way. The iPhone and Android apps also offer an optional ad-free upgrade and a few screens that are still in development, which are not included here.
Limitations of the web version
- Conversions are not saved; there is no history or favourites list
- The appliance calculator uses a fixed rate of $0.25 per kWh for its cost estimate
- The four calculators are in English only, even when the converter is shown in another language
- Food and appliance lists are short, built-in samples and cannot be extended
Phone app
Enecon is also available as an app for phones and tablets: