The size of nuclear explosions can vary significantly based on the type of weapon and its design. The size of a nuclear explosion is typically measured in terms of its yield, which is the amount of energy released. The yield is often expressed in kilotons (kt) or megatons (Mt) of TNT equivalent.

Here are some general categories of nuclear explosion sizes:

Sub-kiloton Yield (less than 1 kt): These are small nuclear explosions, often associated with tactical nuclear weapons or tests of new designs.

Kiloton Range (1 kt to 100 kt): This range includes most early nuclear weapons, such as those used in World War II. For example, the bomb dropped on Hiroshima had an estimated yield of about 15 kt, while the Nagasaki bomb had a yield of around 21 kt.

High Kiloton to Low Megaton Range (100 kt to 1 Mt): These weapons are significantly more powerful than the first atomic bombs. They are typically associated with larger strategic nuclear weapons.

Megaton Range (1 Mt and above): These are very large nuclear explosions, often associated with thermonuclear or hydrogen bombs. The largest nuclear test ever conducted, the Tsar Bomba by the Soviet Union, had a yield of about 50 Mt, though it was originally designed to yield 100 Mt.

Multi-megaton Range (10 Mt and above): Such weapons are rare and have typically only been tested, not deployed, due to their immense destructive power and the political, environmental, and practical implications of using them.

The effects of a nuclear explosion depend not only on its yield but also on factors like the altitude at which it is detonated, the local geography, and weather conditions. The primary destructive effects include blast pressure, thermal radiation, and ionizing radiation.