Reference library · Media planning
Reach
Reach is the number or percentage of people in the target audience exposed to a campaign at least once during a defined period. It counts unique individuals, not exposures, so someone who sees an ad five times still counts as one reached person. Reach is always capped at 100% of the target universe.
Formula
Worked example
Target audience: adults 20-49 in the Czech Republic, universe = 4,000,000. A TV and digital campaign, deduplicated across channels, exposes 2,400,000 unique individuals at least once. Reach = 2,400,000 / 4,000,000 x 100 = 60%. This means 1,600,000 target adults were never exposed, so a media planner weighing whether to add a channel or extend flighting would look here first.
How it is used
Planners set a reach target before deciding frequency, since reach and frequency trade off against each other at a fixed budget. Buyers check reach curves by weekly increments to see when a plan hits diminishing returns, and cross-media plans require a deduplicated reach figure across TV, digital and other channels rather than adding each channel's reach together. The common practical mistake is summing single-channel reach numbers instead of using a deduplicated cross-media reach model, which overstates true coverage because it ignores audience overlap.
The common mistake
Reach is a deduplicated headcount capped at 100% of the target audience, so it should never be confused with GRP or TRP, which measure duplicated exposure volume and can run well past 100%.