What modern fleet buildup would equal the Royal Navy at the end of the Napoleonic Wars?
Short answerBy proportional power, existing leading navies are already comparable; by literal ship count, the cost and manpower requirement would be prohibitive.
NotesA modern equivalent to the Royal Navy at the end of the Napoleonic Wars changes completely with the measure chosen. In firepower or proportional dominance, current fleets already surpass or approximate the old force. A literal rating-for-rating conversion would instead demand roughly eight carriers, seven large amphibious ships, 103 cruisers, 144 destroyers, and 385 frigates. Building that many advanced hulls would consume extraordinary economic capacity. Crewing them would also require compulsory naval service from a large share of the population, showing why raw ship counts are the least useful form of historical equivalence.