Audience Reach Calculator
Reach is the count of real people behind your impressions — not how many times the ad showed, but how many humans it actually touched. Enter impressions and average frequency to recover it, then add your audience size to see what slice of them you covered.
Reach = impressions ÷ frequency. It is the number of unique people exposed to your ad at least once, the human denominator behind a pile of impressions. If you instead know your total audience and a target coverage, reach = audience size × reach %. The two routes answer different questions: dividing impressions by frequency recovers the reach you actually achieved, while multiplying audience by a percentage plans the reach you intend to buy. Reach matters because two campaigns with identical impressions can touch wildly different numbers of people — one spread wide, the other hammering a few.
Reach Calculator inputs and result
How to use this calculator
- Decide which route you needTo recover the reach you achieved, divide impressions by frequency. To plan the reach you want, multiply audience size by a target percentage. This tool runs the first route and reports the percentage when you add an audience.
- Enter impressions and frequencyTake both from the same campaign and window. Frequency is the average exposures per person; if you only have reach and impressions, the frequency calculator gives it to you.
- Read the unique reachThe headline is roughly how many distinct people your campaign touched — the human count behind the impressions, not the impressions themselves.
- Add an audience for contextEnter your total addressable audience and the tool shows reach as a percentage of it — the coverage number planners actually argue about.
- Export for the planCopy a share link, drop the CSV into your reach-and-frequency model, or print a one-page summary for the media review.
RGM Expert Says
Reach is the metric clients say they understand and then quietly confuse with impressions. We spend a surprising amount of an audit untangling the two: impressions count exposures, reach counts people, and the ratio between them is frequency. The moment a team sees that their ‘600,000 impressions’ actually touched only 150,000 humans at a frequency of four, the conversation about whether the campaign is too narrow or too broad finally becomes possible.
There are two honest ways to arrive at a reach number and they answer different questions. Dividing impressions by frequency tells you the reach you got — a backward-looking, measured figure. Multiplying audience size by an intended coverage percentage tells you the reach you are planning to buy — a forward-looking target. We are careful never to mix them in the same sentence, because a planned 70% coverage and a measured 30% reach are very different conversations, and conflating them is how budgets get misallocated.
What we really care about is reach as a share of the audience that matters, not reach in raw millions. A hundred thousand of the wrong people is worse than thirty thousand of the right ones. So we always pull reach back to a percentage of a deliberately defined audience, then weigh it against the frequency it cost. Reach and frequency live on a single fixed budget, and choosing their split — rather than maximising either — is most of the planning craft.
How it works
Reach divides total impressions by average frequency to recover the unique people exposed; an optional audience size turns that into a coverage percentage.
- Impressions — total times the ad was served, repeats included.
- Frequency — average exposures per person.
- Audience size — optional addressable total; turns reach into a coverage percentage.
Recovered reach assumes your average frequency is accurate; a skewed exposure distribution will distort it. For the companion metric, use RGM’s frequency calculator and the CPM deep dive.
Why impressions lie and reach tells the truth
Impressions are the most over-trusted number in media because they sound like people and are not. An impression counts every time an ad renders, repeats included, so a campaign can post an impressive impression total while touching almost nobody new. Reach strips out the repeats and counts humans, which is why two campaigns with identical impressions can reach completely different numbers of people — one spread wide and shallow, the other pounding a small group at high frequency.
Two routes to reach answer two different questions, and the discipline is keeping them apart. Reach = impressions ÷ frequency recovers the reach you actually achieved — a measured, backward-looking fact. Reach = audience size × reach % plans the reach you intend to buy — a forward-looking target against a defined audience. Mixing a planned coverage figure with a measured reach figure is one of the quiet ways media plans drift away from reality.
Reach earns its importance from the evidence that broad reach, not heavy repetition, drives most brand growth — the central argument of Byron Sharp’s work. But reach in raw numbers is hollow; reach as a percentage of the right audience is what counts. And because reach and frequency split one fixed budget, the real decision is never ‘how much reach?’ alone but ‘what balance of reach and frequency serves this goal?’
Two ways to think about reach
Reach has no universal benchmark — healthy coverage depends on your goal and audience. What helps is being clear about which calculation you are running and what it means.
| Route | What you supply | What it answers |
|---|---|---|
| Impressions ÷ frequency | Delivered impressions and average frequency | The unique reach you actually achieved |
| Audience × reach % | Audience size and a target coverage | The reach you are planning to buy |
| Reach as % of audience | Reach and a defined audience size | How much of the right people you covered |
| Reach vs frequency split | A fixed budget | The trade-off you must deliberately choose |
What media thinkers say about reach
Growth comes from reaching the people who barely think about you, not from reaching your fans one more time. Buy width before you buy depth.
Count people, not pixels. An impression total tells you what you served; reach tells you who you actually touched, and only the second one grows a brand.