Convert cal to kWh calories ↔ kilowatt hours Free Online Secure
Type a value in calories and read it in kilowatt hours at once. The factor is exact by definition, the arithmetic happens in your browser, and nothing is sent anywhere.
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Common values — Convert cal to kWh (calories ↔ kilowatt hours)
| cal | kWh |
|---|---|
| 1 | 0.00000116222222222 |
| 2 | 0.00000232444444444 |
| 3 | 0.00000348666666667 |
| 5 | 0.00000581111111111 |
| 10 | 0.0000116222222222 |
| 20 | 0.0000232444444444 |
| 50 | 0.0000581111111111 |
| 100 | 0.000116222222222 |
Where these units come from
Energy collected a unit from every field that discovered it separately. The joule is the SI one and the plainest: a newton acting over a metre. The calorie came from the study of heat and was defined by warming water one degree — which is why there are several of them, depending on which degree you start from; the thermochemical calorie, exactly 4.184 J, is the one used here. The kilowatt hour is not a physicist's unit at all but an accountant's: a kilowatt drawn for an hour, which is how electricity is sold. The BTU is its British cousin, built from the pound and the Fahrenheit degree, and it still runs the heating and cooling trade worldwide.
Where you meet them
Joules belong to physics and to food labels outside the English-speaking world. Kilowatt hours arrive on every electricity bill and describe the capacity of batteries, from a phone to a car. BTUs rate air conditioners, boilers and gas appliances almost everywhere, including in countries that are otherwise entirely metric. Calories — in practice kilocalories — rule nutrition, which is the one place where the unit's name is routinely a thousand times out.
Questions people ask
Is the calorie on a food label the same as the one here?
No, and the difference is a factor of a thousand. The Calorie printed on food is a kilocalorie: a thousand of the calories used on this page. A 500-Calorie meal is 500,000 calories in the physicist's sense, or about 2.1 megajoules. Food labels in most of the world now print kilojoules beside it, which avoids the ambiguity entirely.
Why is a kilowatt hour not just a kilowatt?
Because one is a rate and the other is an amount. A kilowatt is how fast energy flows — a kettle draws about two of them. A kilowatt hour is what you get if that flow continues for an hour, and it is what the meter counts and the bill charges for. Running a 2 kW kettle for six minutes uses 0.2 kWh; running a 10 W lamp all day uses about the same.
Is the answer exact?
Where both units are defined in terms of one another by whole numbers, yes — the page says so above the figure, and the only rounding is in how many digits are shown. Where the ratio has no finite decimal, the page shows twelve significant digits and says the relation is approximate rather than pretending otherwise.
Does anything I type leave my device?
No. The arithmetic runs in your browser; nothing is uploaded and there is no server to upload it to. Load the page once and it keeps working with the network switched off.
Calories to kilowatt-hours: reading fuel specifications and power plant reports
Outside the English-speaking world, fuel is still specified in kilocalories. A coal contract in India or Indonesia gives the heating value in kcal/kg, an Argentine gas bill assumes 9,300 kcal per cubic metre, a Latin American statistician counts energy in tonnes of oil equivalent defined as ten million kilocalories, and a power plant reports its heat rate in kcal per kWh. Whoever wants to set these figures against a European or American price has to turn calories into kilowatt-hours. To convert cal to kWh, multiply by 0.00000116222: 1,000 cal is 0.00116 kWh, 1 kcal is 0.00116 kWh and 1 Mcal is 1.162 kWh. The calculator above multiplies as you type, and the sections that follow show how such figures read in coal, gas and power station data.
Below you will find the rule with examples, short notes on both units, a side-by-side look and a long series of fuel, boiler and power station cases, ending with the slips people make most. Everything is computed locally in the page. For a purchase contract, always apply the basis and the factor that the contract itself states.
How to convert cal to kWh: multiply by 0.00000116222
The rule
One thermochemical calorie is 4.184 joules and one kWh is 3,600,000 joules, so one calorie is 0.00000116222 kWh. To convert cal to kWh, multiply the calories by 0.00000116222: 50,000 cal give 0.0581 kWh, 5 million cal give 5.81 kWh and 250 million cal give 290.6 kWh. For the opposite direction multiply kWh by 860,421.
Calories and kilocalories
Fuel data is almost always in kilocalories, and for a solid fuel kcal/kg and cal/g are the same number. A kilocalorie is 0.00116222 kWh, so a coal of 5,000 kcal/kg holds 5.81 kWh per kilogram. For a million kilocalories, a Gcal, the figure is 1.162 MWh.
Worked examples
A coal sample reading 4,300 cal/g holds 5.0 kWh per kilogram. A cylinder of 14.2 kg of LPG at 11,900 kcal/kg holds 169,000 kcal, 196 kWh. A tonne of oil equivalent of 10 Gcal holds about 11,600 kWh.
A quick sanity test
The answer in kWh is about a millionth of the calorie figure, or about a thousandth of the kilocalorie figure. If a “convert cal to kWh” calculation gave a larger number than you started with, you multiplied by 860,421 instead of 0.00000116222.
The calorie
The unit of fuel data outside the English-speaking world
The calorie is 4.184 joules, close to the heat that warms a gram of water by a degree. Its thousand-fold relative, the kilocalorie, is the unit of heating value in Indian, Latin American, Turkish and many industrial specifications.
Where it appears
Coal and oil specifications, gas contracts, boiler reports and nutrition.
The kilowatt-hour
The unit of electricity and, increasingly, of everything
The kilowatt-hour is exactly 3.6 megajoules. Power markets, bills and battery makers use it, and more and more fuel buyers want their heat quoted in it too.
Where it appears
Bills, meters, tariffs and statistics.
Side by side: calories and kWh
Seen in kWh, a given amount of heat is a million times smaller than in small calories and a thousand times smaller than in kilocalories: 3,000 kcal turns into 3.49 kWh and 20,000 kcal into 23.2 kWh. Both describe identical energy, and only the size of the yardstick changes.
Nothing is lost in the change. People most often trip over the calorie versus the kilocalorie, a gap of exactly 1,000.
Where the conversion shows up
Coal contracts
A shipment of coal specified at 6,000 kcal/kg holds 6.97 kWh per kilogram, so a tonne holds 6.97 MWh. A cheaper grade at 4,200 kcal/kg holds 4.88 kWh per kilogram. Dividing price by energy gives a fair comparison: at 90 US dollars a tonne the 6,000 kcal coal costs 1.29 US cents per kWh of heat. A “convert cal to kWh” calculation is the step behind that figure.
Gas billing
Some countries bill gas by volume at a reference heating value. A cubic metre at 9,300 kcal holds 10.81 kWh, and 9,000 kcal holds 10.46 kWh. A household using 800 cubic metres in a winter month at the first value has used 8,650 kWh.
Plant efficiency
A power station reports its heat rate in kcal of fuel per kWh of electricity. One kWh is 860.4 kcal, so a plant at 2,400 kcal/kWh is 35.8 per cent efficient, one at 2,000 is 43 per cent and a combined-cycle gas plant at 1,650 is 52 per cent.
Gross and net calorific value
The gross value counts the heat recovered when the steam in the exhaust condenses. The net value does not. For natural gas the net value is about 10 per cent lower, for coal 3 to 5 per cent. A coal of 5,500 kcal/kg gross may be 5,300 net, which is 6.16 kWh per kilogram. State the basis beside any convert cal to kWh result.
Waste to energy
Municipal waste has a heating value of 1,200 to 1,800 kcal/kg. At 1,500 kcal/kg a tonne holds 1.74 MWh of heat, and a plant that converts a quarter of it to electricity makes about 436 kWh per tonne. A city dumping 1,000 tonnes a day thus has around 436 MWh a day available.
Cement kilns
Kilns consume about 750 kcal of fuel for every kilogram of clinker, which is 0.87 kWh. A tonne of clinker needs 872 kWh of heat. A large kiln of 5,000 tonnes a day therefore takes 4.36 GWh of fuel energy every day, which is why plants burn waste fuels when permitted.
The tonne of oil equivalent
The Latin American tep and the international toe are defined as ten million kilocalories, 10 Gcal, which is about 11,600 kWh or 41.87 GJ. A country that reports 25 million toe has 290 TWh of primary energy. A “convert cal to kWh” calculation converts such a figure to the TWh that a European statistician would quote.
A steam boiler load
Saturated steam at 10 bar absolute holds about 663 kcal/kg and feedwater at 80 °C about 80, so each kilogram of steam takes 583 kcal. A boiler making 10 tonnes an hour needs 5.83 Gcal an hour, 6.78 MWh. With coal at 4,000 kcal/kg and 80 per cent efficiency it burns 1.82 tonnes an hour.
Fuel switching
To replace a tonne of coal at 4,000 kcal/kg with LPG at 11,900 kcal/kg you need 336 kg of gas. In kWh both stand for 4,650. Plants compare the delivered price per kWh of heat, not per tonne, and the cheaper fuel per tonne is often the dearer per kWh.
Price per kWh of heat
Divide the price per kilogram by the kWh per kilogram. Coal at 90 dollars a tonne and 6,000 kcal/kg gives 1.29 cents. LPG at 1.2 dollars a kilogram and 11,900 kcal/kg gives 8.7 cents. Natural gas at 10 dollars per MMBtu gives 3.4 cents. A fuel table in kcal makes sense only after this step.
Pulverised coal and ash
Ash dilutes coal. A coal with 40 per cent ash may read 3,500 kcal/kg, 4.07 kWh, while a washed coal at 15 per cent ash reads 5,500, 6.39 kWh. Burning the first requires 57 per cent more mass for the same heat, and that mass leaves as extra ash to dispose of. A “convert cal to kWh” calculation per kilogram makes the penalty plain.
Thermal and electrical kWh
A kWh of heat and a kWh of electricity are not equal in value. Electricity costs two to four times as much, because it takes 2.5 to 3 kWh of fuel heat to make one. When a fuel table is converted from kcal to kWh, the answer is a thermal kWh.
Bomb calorimeter readings
A laboratory bomb calorimeter reports cal/g, which numerically equals kcal/kg. A coal that reads 5,200 cal/g holds 6.04 kWh per kilogram. Repeat tests on one sample usually agree within a few tens of cal/g, which is about 0.03 kWh per kilogram.
A little nutrition
Food labels use the same kilocalorie. A meal of 1,000 kcal holds 1.16 kWh and a day's food of 2,000 kcal holds 2.32 kWh. A smartphone charge of 15 Wh is only 13 kcal, about the energy in a quarter of a biscuit.
Moisture and the dry basis
Heating value depends on how the coal is reported. A coal of 4,000 kcal/kg as received with 10 per cent moisture would read about 4,444 kcal/kg on a dry basis, which is 5.17 kWh per kilogram instead of 4.65. Contracts name the basis, and a buyer converting to kWh should use the one that was delivered.
Brick kilns and lime
Firing bricks takes roughly 400 to 600 kcal per kilogram of product in efficient kilns, 0.46 to 0.70 kWh. A kiln making 50 tonnes of bricks a day consumes 23 to 35 MWh of fuel heat. In small village kilns the figure can be twice that.
The mental shortcut
To convert cal to kWh in your head, divide the kilocalories by 860. For 5,000 kcal: 5,000 / 860 = 5.81 kWh, against the exact 5.81. For small calories divide by 860,000. The slip is about 0.05 per cent.
Spreadsheet formulas
In a spreadsheet, keep the calories in column A and use =A2*0.00000116222 in column B. For kilocalories use =A2*0.00116222, and for Gcal =A2*1162.22 gives kWh. A column that converts back with =B2*860420.65 is a free consistency check.
Rounding in reports
Heating values are given to the nearest 50 or 100 kcal/kg, so quote the kWh to three figures. 4,300 kcal/kg is 5.00 kWh, not 4.9975. Extra digits suggest an accuracy that no coal sample has, as seams and stockpiles vary by hundreds of calories.
Landmarks to memorise
1,000 kcal is 1.162 kWh. A Mcal is 1.162 kWh. A Gcal is 1.162 MWh. A toe is 11.6 MWh. 6,000 kcal/kg is 6.97 kWh/kg. 4,000 kcal/kg is 4.65 kWh/kg. With these landmarks most mental convert cal to kWh work is possible.
Reference ladder
100 kcal: 0.116 kWh. 500 kcal: 0.581 kWh. 2,000 kcal: 2.32 kWh. 8,500 kcal: 9.88 kWh. 12,000 kcal: 13.9 kWh. 100,000 kcal: 116.2 kWh. 1,000,000 kcal: 1,162 kWh. A list like this lets you test a calculator at a glance.
Checking by reversing
To check a “convert cal to kWh” calculation result, multiply the answer by 860.42 for kilocalories. If 12,000 kcal gave 13.9 kWh, then 13.9 × 860.42 = 11,960, close to 12,000. A second test is size: the kWh figure must be about one thousandth of the kilocalorie figure.
Link to MJ and BTU
A kilocalorie is 4.184 kJ and 3.968 BTU. Therefore 5,000 kcal is 20.9 MJ, 19,840 BTU and 5.81 kWh. With the International Table calorie of 4.1868 J a megacalorie is 1.1630 kWh instead of 1.1622, which is 0.07 per cent more.
A worked example
A factory burns 20 tonnes of coal a day at 4,500 kcal/kg. That is 90 Gcal, which is 104.6 MWh of heat in the fuel. If its boiler is 82 per cent efficient it delivers 85.8 MWh to the process, so each tonne of product that needs 500 kWh of process heat takes about 0.12 tonnes of coal.
Two routes to one answer
You can get to kWh straight from the calories with 0.00000116222, or via joules: multiply by 4.184 and divide by 3,600,000. For kilocalories the MJ route is 4.184 / 3.6 = 1.16222 MWh per Gcal. If the two routes disagree, a digit was copied wrongly.
Heat rate and efficiency
Efficiency is 860.42 divided by the heat rate in kcal/kWh. A subcritical coal plant at 2,400 gives 35.8 per cent, supercritical at 2,250 gives 38.2 per cent and ultra-supercritical at 2,000 gives 43 per cent. Each 100 kcal/kWh saved raises efficiency by roughly 1.5 to 2 percentage points at these levels.
Coal burned by a power plant
A plant of 500 MW with a heat rate of 2,400 kcal/kWh burning coal of 4,000 kcal/kg uses 0.6 kg per kWh, which is 300 tonnes an hour. Running at 80 per cent of capacity, it burns about 2.1 million tonnes a year, around 9.8 TWh of heat in the fuel.
Liquid fuels
Typical heating values are fuel oil 9,800 kcal/kg, diesel 10,200 and petrol 10,500. These are 11.4, 11.9 and 12.2 kWh per kilogram. Diesel weighs about 0.84 kg per litre, so a litre holds 8,570 kcal, nearly 10 kWh. A small generator at 35 per cent efficiency turns that litre into 3.5 kWh of electricity.
Cooking gas cylinders
LPG holds about 11,900 kcal/kg, 13.8 kWh. The 14.2 kg domestic cylinder common in India holds 169,000 kcal, 196 kWh, and a 19 kg commercial cylinder 226,000 kcal, 263 kWh. A family using one cylinder a month burns about 6.5 kWh a day.
Natural gas around the world
Gas has a heating value of 8,500 to 10,000 kcal per cubic metre depending on its source: pipeline gas rich in ethane sits higher, gas with nitrogen lower. In kWh that is 9.9 to 11.6 per cubic metre. The spread is why contracts pin the reference value.
Biogas
Biogas with 60 per cent methane holds about 5,100 kcal per cubic metre, which is 5.9 kWh. A farm digester making 500 cubic metres a day produces 2,960 kWh of heat, or 2.55 million kcal. Burned in an engine at 35 per cent efficiency, it gives about 1,000 kWh of electricity a day, and a “convert cal to kWh” calculation is what turns the plant's gas meter reading into that figure.
Biomass fuels
Rice husk has about 3,000 kcal/kg (3.5 kWh), bagasse at half moisture 2,200 (2.6 kWh), air-dried firewood 3,500 (4.1 kWh) and wood pellets 4,200 to 4,600 (4.9 to 5.3 kWh). A mill that burns 100 tonnes of husk an hour releases 349 MWh of heat in that time.
More values for convert cal to kWh
A longer list of conversions
If the value you need is not in the first list, these further conversions may be close enough to read off directly:
- 0.1 cal = 0.000000116222 kWh
- 0.5 cal = 0.000000581111 kWh
- 3 cal = 0.00000348667 kWh
- 4 cal = 0.00000464889 kWh
- 7 cal = 0.00000813556 kWh
- 15 cal = 0.0000174333 kWh
- 20 cal = 0.0000232444 kWh
- 75 cal = 0.0000871667 kWh
- 200 cal = 0.000232444 kWh
- 500 cal = 0.000581111 kWh
- 2,000 cal = 0.00232444 kWh
- 10,000 cal = 0.0116222 kWh
Common slips with a “convert cal to kWh” calculation
Calorie or kilocalorie
The factor 0.00116 belongs to kilocalories and 0.00000116 to small calories. A coal specification saying "5,000 calories" almost always means kcal/kg.
Gross or net
Two quotes for the same gas, one gross and one net, can differ by 10 per cent. Convert both to kWh and compare like with like before you judge a price.
Heat and electricity
The kWh you get from a fuel table is heat. The electricity produced by burning it is a third or less of that, so do not count a kilogram of coal as 6 kWh of electric power.
Quick answers
How do I convert cal to kWh?
Take calories times 0.00000116222, or kilocalories times 0.00116222.
What is 1,000 kcal in kWh?
It is 1.162 kWh.
What is a Gcal in kWh?
It is 1,162 kWh, or 1.162 MWh.
How many kcal make one kWh?
860.4 kcal make one kWh.
Is my number sent anywhere?
No, everything is computed in the browser.
Related pages
Other energy conversions are listed in Convert cal to J, Convert J to kWh, Convert BTU to kWh, Convert kWh to J, Convert km to mi, Convert mi to km, Convert °C to °F, Convert °F to °C, Convert ft/s to km/h. Going the other way is covered by Convert kWh to cal.
To sum up, a “convert cal to kWh” calculation needs one multiplication by 0.00000116222 and a unit beside the answer. The figure is worked out on your own device, without registration or upload.