toolbox
Home / Sales, Marketing & Audience / Facebook Reach Calculator

Facebook Reach Calculator

The Facebook Reach Calculator estimates what share of a defined eligible audience received content at least once. It is intended for campaign and page reporting where both unique reach and a meaningful audience base are available.

The denominator must represent the population you actually want to evaluate—such as a targetable campaign audience—not an unrelated follower or national population total. The resulting reach rate helps compare distribution breadth, while the unreached count highlights remaining audience opportunity. It does not describe how many times people saw the content or whether they engaged, so pair it with frequency, impressions, and outcome metrics.

Reach and audience totals

Result
—
Audience reach rate
Audience not reached—
Reached per 1,000 eligible—

1. Define the eligible audience for the

Define the eligible audience for the campaign, market, or page analysis.

2. Enter unique people reached during the

Enter unique people reached during the selected reporting window.

3. Enter the corresponding eligible audience size

Enter the corresponding eligible audience size using the same geography and targeting scope.

4. Review the reach percentage and unreached

Review the reach percentage and unreached audience; investigate mismatched scopes if reach exceeds the audience.

Audience reach rate (%) = People reached ÷ Eligible audience size × 100
Audience not reached = Eligible audience size − People reached

This model assumes reached people belong to the entered eligible audience and caps reach at that audience size.

What the result means

The primary result reports audience reach rate from the values entered above. Supporting rows show useful components or equivalent rates.

Use inputs from one consistent reporting scope. Platform definitions, attribution settings, rounding, and incomplete tracking can affect comparisons.

Given: 138,000 people reached from an eligible audience of 600,000.

Calculation: Reach rate = 138,000 ÷ 600,000 × 100 = 23.00%. Unreached = 600,000 − 138,000 = 462,000.

Result: The content reached 23% of the defined eligible audience.

Is eligible audience the same as follower count?

Only when followers are intentionally the population being evaluated. A paid campaign’s targetable audience is often a better denominator.

Why is reach unique but impressions are not?

Reach counts deduplicated people, while impressions count every display, including repeat delivery.

Can the reach rate exceed 100%?

Not under this defined-audience model. If it does in source reports, the reach and audience scopes likely differ.

Does a low reach rate mean poor creative?

Not by itself. Budget, bid strategy, target size, placements, schedule, and delivery constraints also affect reach.

How does this relate to frequency?

Reach measures breadth. Frequency divides impressions by reach to describe average repetition among reached people.