How much of each navy fought

What share of British and French naval strength did the opposing fleets represent?

About 40 percent for France and roughly 20 to 30 percent for Britain.

The French force represented roughly 40 percent of its navy, while the British force represented about 20 to 30 percent. These deliberately approximate estimates establish the scale of the commitment on both sides. France was risking a particularly large share of its effective fleet in support of the invasion scheme. Quiberon Bay was therefore a strategic concentration of naval power rather than an isolated squadron action.