Billboard CPM calculator
Work out what a face costs per thousand impressions — or what to charge to hit a CPM you can defend. Free, nothing saved, no sign-in.
How the number is worked out
CPM is cost per thousand impressions — total media cost divided by total impressions, times 1,000. Everything else on this page is bookkeeping around those two figures.
Impressions come from the face's daily audience multiplied by the days it runs: a 4-week period is 28 days, so a face delivering 40,000 a day delivers 1,120,000 in a period. Multiply by the number of faces and the number of periods for the campaign total.
Three things this gets right that a back-of-envelope usually doesn't
- Out-of-home is bought in 4-week periods, not calendar months — and there are 13 of them in a year, not 12. Treating a per-period rate as a monthly rate understates an annual buy by a full period. That is one of the most common arithmetic errors in an OOH proposal.
- Production and install are real money the advertiser pays. Media CPM covers the space; the vinyl and the crew are separate. On a one-period flight, production can move the effective CPM sharply — which is why both figures are shown. On a twelve-period buy it barely registers.
- Impressions are exposures, not people. The same commuter passing every morning is counted every morning. CPM is a cost-efficiency measure, not a reach measure — how many different people you touched, and how often, is a separate question your Geopath data can answer.
DEC or Geopath impressions?
DEC — daily effective circulation — is the older figure, derived from traffic counts adjusted for vehicle occupancy and how visible the face actually is. Geopath (formerly the Traffic Audit Bureau) provides audited impressions, and is what most national buyers now expect to see. Either plugs into a CPM the same way. What matters is being consistent: comparing a DEC-based CPM on one face to a Geopath-based CPM on another is comparing two different things.
Using CPM as an operator
The most useful thing about CPM is that it makes two faces comparable. If one board's CPM is far above comparable inventory nearby, it will be a hard sell no matter how good the rate card looks; if it is far below, you are probably leaving money on the table. As the pricing guide puts it — the metric that actually pays you is occupancy × rate, and CPM is how you keep the rate honest.
Put your inventory to work
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Start free trialFrequently asked questions
How do you calculate billboard CPM?
CPM is the cost of reaching a thousand impressions: divide the total media cost by the total impressions, then multiply by 1,000. For a billboard, impressions come from the face's daily audience (DEC or an audited Geopath figure) multiplied by the days it runs. A face delivering 40,000 impressions a day over a 4-week period delivers 1,120,000 impressions; at $2,800 for that period the CPM is $2.50.
What is a 4-week period in out-of-home?
Out-of-home is bought in 4-week periods rather than calendar months. There are 13 four-week periods in a year, not 12, so a rate quoted per period is not the same as a monthly rate — an annual buy at a per-period rate costs thirteen times that rate, not twelve.
What is DEC on a billboard?
DEC stands for daily effective circulation — the average number of people per day with a reasonable opportunity to see the face, traditionally derived from traffic counts adjusted for vehicle occupancy and visibility. Modern OOH increasingly uses audited Geopath impressions instead. Either plugs into a CPM the same way; just be consistent about which one you use.
Does billboard CPM include production and installation?
Media CPM usually does not — it covers the space rental only. But the advertiser pays for vinyl printing and installation too, so the effective CPM they actually experience is higher. On a short flight production can move the number a long way, which is why it is worth showing both.