One megawatt is exactly 1,000 kilowatts. It is a plain decimal step, and the reason it deserves a page is scale: the megawatt is where individual appliances give way to power stations, and misplacing the prefix by one step misplaces a project by a factor of a thousand.
About the units
Both are the watt with a prefix — kilo for a thousand, mega for a million. The megawatt is the working unit of electricity generation and large industrial loads. A single large wind turbine is 5 to 15 MW, a gas turbine 100 to 500 MW, and a nuclear reactor 1,000 to 1,600 MW. Above it the gigawatt describes national grids: peak demand in Sweden is around 25 GW, in Britain around 45 GW. Below it the kilowatt covers buildings, vehicles and machines.
The exact factor
The factor is exactly 1,000. The distinction to hold onto at this scale is between power and energy, because both appear with the same prefixes: a 100 MW plant running for an hour produces 100 MWh, and running for a year at full output produces 876 GWh. Capacity factor complicates it further — a wind farm rated at 100 MW typically delivers 30 to 45 per cent of that on average, so its annual output is well below the theoretical maximum. Comparing a plant's nameplate rating to another's actual generation is a common error in energy journalism.
Where you meet this conversion
Electricity generation, grid planning and large industrial installations. Data centre capacity is quoted in megawatts, which is a power rating for the whole facility including cooling. Electric vehicle charging hubs, electrolysers and industrial furnaces are specified in megawatts while their individual components are in kilowatts. District heating plants use the same pair for thermal output.