CPM (Cost per mille)
CPM is how much you pay for one thousand times your ad is shown. CPM stands for cost per mille. Mille is Latin for thousand, so people also say cost per thousand. If you spend $5 and the ad is shown 1,000 times, CPM is $5. One showing is called an impression. CPM is a way to price ads. It does not prove those views were useful.
Theodor Lindfors, Founding Marketer ·
Formula
CPM = (ad spend / impressions) × 1,000
How to calculate CPM
An impression is one time your ad was shown. Divide ad spend by impressions, then multiply by 1,000 so you are talking about a block of a thousand views. Mille is Latin for thousand. That is why people say CPM (cost per mille) instead of spelling out cost per mille. If you landed here looking for the critical path method from project management, this page is about ads.
Let's take a drink brand as an example. They sell a low-sugar sports drink for active women over 50, mostly from their own website. The drink brand spends $500 on Instagram ads. Those ads are shown 100,000 times in the feed (the scrolling list of posts). $500 ÷ 100,000 = 0.005 per view. Multiply by 1,000 and CPM (cost per mille) is $5.
On paid social (Instagram, Facebook, TikTok) you usually buy views, so CPC (cost per click) is CPM (cost per mille) shaped by CTR (click-through rate: how often a view becomes a click). Same auction, different unit.
Compare CPM (cost per mille: the price of a thousand views) inside one platform and one placement. Let's take a drink brand as an example. They sell a low-sugar sports drink for active women over 50, mostly from their own website. A cheap CPM on random websites is not a win against an Instagram feed that actually sells the drink brand's sports drink.
Why CPM matters
Paid social and video ads are often bought on views. CPM (cost per mille) is the sticker price of attention. Let's take a drink brand as an example. They sell a low-sugar sports drink for active women over 50, mostly from their own website. When the drink brand's CPM jumps, one of three things happened:
- The auction got more expensive, because more drink brands were bidding for the same women.
- The platform decided the ad was lower quality, so it charges more to show it.
- The same people are seeing the same video too often.
Media buyers use CPM (cost per mille) to compare placements (Instagram feed vs stories vs a cheap display network). Creative teams use CPM as a fatigue alarm. Finance barely cares, until the same $500 buys fewer views and CPA (cost per acquisition: ad spend divided by orders) follows. That is the chain: CPM up, reach down, results worse. Let's take a drink brand as an example. They sell a low-sugar sports drink for active women over 50, mostly from their own website. If the drink brand's $500 Instagram buy used to buy 100,000 views and now buys far fewer, orders usually follow the views down.
How to read CPM
Read CPM (cost per mille: the price of a thousand views) with ad frequency (how many times the average person has seen the ad) and click-through rate (CTR: how often a view becomes a click). Frequency up, CTR down, CPM up is the classic creative fatigue pattern: people are bored of the video, so Meta (Facebook and Instagram) charges more to keep showing it. CPM up with CTR holding can just be seasonality or a competitive burst around New Year fitness ads.
The useful question for CPM (cost per mille) is this: what did we pay for a thousand of the views we meant to buy?.
Common CPM mistakes
- Treating the cheapest CPM (cost per mille) as the best placement. Junk inventory is cheap because nobody is watching.
- Raising budget on a tired video because yesterday's CPM still looked fine. Let's take a drink brand as an example. They sell a low-sugar sports drink for active women over 50, mostly from their own website. Pouring more of the drink brand's $500 into a video people have already seen is how CPM and cost per order both rise.
Lemonado
How Lemonado helps with CPM
Rising CPM (cost per mille: the price of one thousand ad views) is a symptom. Lemonado lets you see CPM next to frequency (how many times the average person has seen the ad), click-through rate (CTR: how often a view becomes a click), and fatigue scores on the same ad, so you rotate instead of pouring more budget into a tired one.
Ask why CPM (cost per mille) jumped on Meta (Facebook and Instagram ads) this week and you get the ad-level view, not a campaign average that hides the one ad burning the audience.