"Lower CPM means cheaper traffic" — the myth that hid my real costs

"Lower CPM means cheaper traffic" — the myth that hid my real costs

Media buyers chase low CPM like it's the scoreboard. I chased it into a campaign that looked cheap and bled money.

The setup
Two identical offers, two placements. Placement A: $4 CPM. Placement B: $11 CPM. Obvious choice, right?

The move
I ran both for a week and measured cost per conversion instead of cost per thousand impressions.

The numbers
Placement A ($4 CPM): 0.3% CTR, 0.8% landing conversion = $52 cost per sale. Placement B ($11 CPM): 1.9% CTR, 2.4% conversion = $24 cost per sale. The "expensive" placement was less than half the real cost. I'd wasted $1,600 on the cheap one before checking.

The lesson
CPM is the price of attention, not the price of a customer. Cheap impressions in front of the wrong people are the most expensive traffic there is.

What I'd do differently
I never compare placements on CPM again — only on cost per acquisition. Low CPM is a vanity metric that feels like thrift and acts like a leak. Numbers illustrative; the inversion happens constantly.