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Playbooks · Media planning

Set frequency to hit an effective reach target

This job converts a brief's effective reach target into the GRP level, average frequency, and budget needed to deliver it. It feeds the GRP allocation and budget sign-off decision before the plan goes to buying.

What you need first

  • The effective frequency threshold and reach percentage target from the brief (e.g. 60% at 3+) — media brief
  • The reach and frequency curve for the selected channel mix and target audience — reach-and-frequency planning tool (Kantar, Nielsen, or in-house model)
  • The cost-per-GRP rate for the market and channel — rate card or negotiated buy sheet
  • The target audience size and campaign flight length — media plan brief
  • The approved budget ceiling — client brief or budget sign-off

The procedure

  1. Extract the effective frequency threshold and reach percentage from the brief
  2. Pull the reach curve for the actual channel mix and audience being bought from the planning tool
  3. Locate the GRP level where the curve crosses the target effective reach percentage, interpolating between the two nearest points
  4. Derive average frequency at that GRP by dividing GRP by the 1+ reach percentage at the same point
  5. Check the frequency distribution for skew from dominant channels before locking the GRP figure
  6. Cost the required GRP against the rate card to produce the required budget
  7. Compare the required budget to the ceiling and adjust flight length, media mix, or target if it falls short

Worked through with numbers

Brief: reach 60% of adults 25-54 (population 10,000,000) at 3+ frequency over a 4-week TV flight, CPP €1,200. Curve from the planning tool for this audience: 700 GRP gives 56% 3+ reach and 80% 1+ reach; 800 GRP gives 61% 3+ reach and 83% 1+ reach. Interpolating for 60% 3+ reach: 700 + (60-56)/(61-56) × 100 = 780 GRP. Interpolating 1+ reach at 780 GRP: 80 + 0.8 × (83-80) = 82.4%. Average frequency among the reached = 780 ÷ 82.4 = 9.5 OTS. Budget = 780 × €1,200 = €936,000. Reached population at 60% 3+ = 6,000,000 people exposed three or more times. If €936,000 sits inside the approved budget, lock the plan at 780 GRP; if not, extend the flight to spread the same GRP at lower weekly cost or narrow the audience definition to raise the curve's crossover point.

Where it goes wrong

  • Average frequency (GRP ÷ 1+ reach) is not effective frequency; read the 3+ reach value directly off the curve at the target GRP instead of assuming an average OTS of 3 means 60% saw the ad three times
  • A reach curve built for one media mix does not transfer to another; rebuild the curve when the channel mix or targeting changes instead of reusing a saved crossover point
  • Locking GRP before flight length ignores that spreading the same GRP over more weeks lowers weekly reach and reshapes the curve; fix flight length first, then size GRP against that flight

How to know it is right

Re-read the 3+ reach value directly off the curve at the finalized GRP level and confirm it meets or exceeds the brief's target before the plan goes to buying.

Terms used

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