What US-level defense spending could buy Britain

What could Britain do if core military spending as a share of GDP matched the United States?

It could expand forces dramatically, potentially beyond a simple doubling, because many fixed support and procurement costs are already being paid.

The hypothetical comparison excludes pensions, war graves, and similar charges from British defence spending. The estimate allows armed-force growth of roughly 100 percent or possibly more, alongside higher pay. Supporting four carriers rather than two illustrates the argument: another dry dock might be needed, but much of the underlying infrastructure would already exist. Fixed procurement and support costs would consequently be spread across a larger force.