Reach counts unique users rather than total impressions, so it never exceeds impressions and typically stays well below it once a campaign has run for more than a day or two. It's the denominator used to calculate frequency and is a key input when judging whether an audience is saturated.
Agencies scaling spend in a limited geography watch reach against total addressable audience size; when reach approaches audience size and CPMs start climbing, it signals the campaign needs a broader or lookalike audience rather than more budget on the same one.

We don't talk. We solve.
Private Meta infrastructure for buyers spending $100,000+ a month. Unlimited accounts, our cards, a 24/7 operator line.