Radio has been the default answer for Jamaican advertisers for decades. It is familiar, it is measurable in a rough way, and everyone knows what a spot costs. Billboards get compared to it constantly, usually badly — because the two are almost never compared on the same basis.
This article sets out how to compare them properly using cost per thousand, and where each channel genuinely wins.
What cost per thousand actually measures
CPM is the cost of reaching one thousand people. The formula is simple:
CPM = (total cost / total impressions) x 1,000
Its value is that it makes unlike things comparable. Its danger is that it flattens a real difference: an impression is not a unit of attention. A radio spot heard in full is not the same as a billboard glimpsed for two seconds, and neither is the same as a billboard seen twice a day for three months by the same commuter.
Use CPM to sanity-check efficiency. Do not use it to decide strategy on its own.
Working out billboard CPM
You need two numbers: the monthly rate for the site, and its daily audience.
Daily audience comes from traffic counts. Take vehicles passing the site per day, multiply by an occupancy factor of roughly 1.5 people per vehicle in Jamaica, then adjust for the share with a genuine opportunity to see the board. Multiply by thirty for the month.
Billboard CPM = (monthly rate / monthly impressions) x 1,000
Because a billboard runs continuously, monthly impressions accumulate fast. This is why outdoor typically shows a very low CPM against broadcast, and also why CPM alone flatters it.
Working out radio CPM
Radio is bought as spots, so you need the spot rate, the number of spots and the average audience for that daypart.
Radio CPM = (total schedule cost / total impressions) x 1,000
The complication is that radio audience varies enormously by station, time of day and programme. A drive-time spot on a major Kingston station and a mid-morning spot on a regional one are different products at similar prices, so always ask which daypart an audience figure refers to.
Ask us for traffic counts on any site you are considering, and ask the station for its audience source. Then run both through the same formula.
The comparison CPM does not capture
Radio can say more
A thirty-second spot carries perhaps seventy words. A billboard carries six. If your proposition needs explaining — a complex product, a rate, a set of terms — radio does something outdoor cannot.
Billboards cannot be skipped
Radio listeners change station during ad breaks. Streaming has eroded live radio further. A billboard on the route home is not avoidable in the same way; the audience is captive by geography rather than by attention.
Billboards are geographically precise
A radio spot reaches everyone in the signal area. A billboard on Constant Spring Road reaches people on Constant Spring Road. For a business whose catchment is one corridor — a restaurant, a branch, a dealership — that precision is the whole point. Browse by parish on the locations map.
Radio is faster to change
A script can be rewritten and re-recorded in a day. Static billboards cannot. Digital billboards close most of that gap.
Frequency works differently
Radio buys frequency by repetition within a schedule. Outdoor gets frequency for free from routine — the same commuters pass the same board twice a day, every working day. Over a month that is roughly forty exposures to the same person, at no additional cost.
Where each one earns its place
Choose radio when the message needs explaining, the offer changes often, you need island-wide coverage quickly, or you are targeting by demographic rather than geography.
Choose outdoor when your catchment is geographic, the message is simple, you want sustained presence rather than a burst, or you need to be visible at the moment someone is near your location.
Use both when you can. Radio explains, outdoor reminds. A campaign that runs radio for the argument and billboards for the recall generally beats either alone at the same total spend.
Before you commit
Ask both channels for the same three things: the rate, the audience figure, and the source of that audience figure. Any medium that cannot tell you where its numbers come from is asking you to take reach on trust.
Our ROI breakdown takes this further, and our comparison with social media advertising covers the third channel most Jamaican advertisers are weighing.
Ask us for traffic counts on any site you are considering.