The United States holds the largest nuclear generating fleet in the world at 97 gigawatts of net capacity across 94 reactors, according to International Atomic Energy Agency Power Reactor Information System data compiled by Visual Capitalist. The US total is more than half again the size of the next largest fleet.

France ranks second at 63 GW from 57 reactors. China follows at 55 GW, also from 57 reactors, with the difference in output reflecting average unit size and fleet composition. Russia holds 27 GW across 36 reactors and South Korea holds 26 GW across 26 reactors. Those five countries account for 71 percent of global nuclear capacity.

The reactor count comparison shows how US fleet economics differ from the rest of the field. American operators run 94 units to produce 97 GW, an average of just over 1 GW per reactor, which reflects the large light water designs commissioned during the 1970s and 1980s and the capacity uprates applied to them since. Canada operates 17 reactors for 13 GW and Japan operates 14 reactors for 13 GW.

Smaller fleets fill out the balance. Ukraine holds 13 GW across 15 units, Spain and Sweden each hold 7 GW, the United Kingdom holds 6 GW, and the United Arab Emirates has reached 5 GW from four reactors. The remainder of the world accounts for 18 GW spread across 28 reactors. The data reflects operating capacity as of June 2025 and excludes units under construction.

Source: Visual Capitalist - https://www.visualcapitalist.com/ranked-nuclear-power-capacity-by-country-2025/