Megawatt-hours to Calories (MWh to cal)

1 megawatt-hour equals 860,420,650.1 calories (rounded).

1 megawatt-hour = 860,420,650.1 calories

How to convert megawatt-hours to calories

To convert megawatt-hours to calories, multiply the number of megawatt-hours by 860,420,650.1. The factor is rounded to 10 significant digits. To go the other way, multiply calories by 1.162222222×10⁻⁹ (rounded).

calories = megawatt-hours × 860,420,650.1

Example: 10 megawatt-hours = 8,604,206,501 calories.

The 'calorie' on food labels is really a kilocalorie. The thermochemical calorie (4.184 J) is used here unless marked IT.

About these units

Megawatt-hour (MWh)

Metric (SI)Current unit

1,000 kilowatt-hours. Used for power-plant output and wholesale electricity trading.

A megawatt-hour is a thousand kilowatt-hours, and it is where electricity stops being a household quantity and becomes an industrial one. It is the energy of a 1 MW load running for an hour, equal to 3.6 GJ, and it is used for metering large industrial customers and for the output of power plants.

The average US household used 893 kWh a month in 2020, so one megawatt-hour is a little more than a month of an ordinary home's electricity. Scaled up further, sustaining about 114 MW for a full year amounts to one terawatt-hour, the unit used for national generation figures.

Indian usage gives a neat link: a million of what Indians call units, meaning kilowatt-hours, is a gigawatt-hour, which is 1,000 MWh. Wholesale deals, plant ratings and grid statistics are typically quoted at this scale because the numbers stay readable.

1 megawatt-hour = 3,600,000,000 joules (exactly).

Sources: Wikipedia: Kilowatt-hour; Wikipedia: Watt-hour; Wikipedia: Orders of magnitude (energy)

Calorie (cal)

ScientificTraditional unit (still used in some regions)

The thermochemical calorie: exactly 4.184 joules, the energy to raise one gram of water by one degree Celsius. Not the same as the food Calorie, which is a kilocalorie.

Latin calor, meaning heat, supplied the name. Nicolas Clement used it in lectures on heat engines between 1819 and 1824, and by 1852 Pierre Favre and Jean Silbermann applied it to the small unit based on a single gram of water warmed by one degree Celsius. Because the specific heat of water varies slightly with temperature, early calories differed from one laboratory to the next. A mean value near 4.1855 J was published for the 15 degree calorie in 1950, with an uncertainty of 0.0005 J.

Chemists settled the matter by definition. The thermochemical calorie is exactly 4.184 J, which is the figure used here, and NIST lists it with that exact value. The calorie is not an SI unit and is regarded as obsolete, since the ninth General Conference on Weights and Measures in 1948 preferred the joule for heat. One thousand of these calories make a kilocalorie, the larger unit used for food, and a slightly larger calorie, the International Table version of 4.1868 J, is used in steam tables.

1 calorie = 4.184 joules (exactly).

Sources: Wikipedia: Calorie; NIST SP 811, Appendix B.8 (energy conversion factors)

Related conversions

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