Cost Per Mille (CPM)
Cost per mille is the price per 1,000 ad impressions. It is the standard pricing unit for display, video and social advertising, and the baseline for comparing.
Cost per mille is the cost an advertiser pays for one thousand impressions of their ad, and it is the standard unit of comparison for any advertising bought on a reach or visibility basis.
What Cost Per Mille Means in Marketing
CPM is how most digital display, video and social advertising is priced and compared. The mille is Latin for thousand, so CPM is the cost for every thousand times an ad appears on a screen, regardless of whether anyone clicks.
Before digital advertising, CPM was already the standard for television, print and radio. A newspaper could tell you how much it cost to put your message in front of a thousand readers. Digital media adopted the same unit because reach and frequency were familiar concepts for media buyers.
CPM is a buying mechanism, not a performance measure. A 50 CPM on Instagram means you pay 50 for every thousand people who see your ad. Whether those impressions do anything is a separate question, answered by engagement rate, click-through rate and ultimately conversion.
The reason CPM matters even for performance marketers is that understanding your cost per impression helps you reverse-engineer the rest. If your CPM is 100 and your CTR is 1%, you are paying 10 per click. If your conversion rate from those clicks is 5%, you are paying 200 per conversion. You can trace the chain back to CPM.
How Cost Per Mille Works
The formula:
CPM = (Total Ad Spend ÷ Total Impressions) × 1,000
So if you spend 5,000 and receive 500,000 impressions, your CPM is 10.
CPMs vary dramatically by:
- Platform. LinkedIn is typically among the most expensive. Open web display is typically among the cheapest.
- Audience. Narrow, high-value audiences cost more. A retargeting audience of website visitors has a higher CPM than a broad prospecting audience.
- Ad format. Video generally commands a higher CPM than static images. Stories and Reels formats differ from feed placements.
- Time of year. CPMs rise in peak retail periods like Q4 and Diwali season in India as advertisers compete for the same inventory.
Cost Per Mille Example
A brand awareness campaign for a new product launch might buy reach on YouTube at a CPM of 80, serving a 30-second ad to a targeted demographic. The goal is not clicks: it is putting the brand name and product in front of the right people enough times to register in memory. CPM is the right pricing model for that goal, because you are paying for eyeballs, not actions.
Why Cost Per Mille Matters for Marketers
CPM is the language media buyers and publishers share. Understanding it stops you being surprised by how digital inventory is priced and lets you make meaningful comparisons between channels. A 500 CPM on LinkedIn might still be worthwhile if those are the exact decision-makers you cannot reach anywhere else. A 10 CPM on display might be worthless if no one in the audience will ever buy from you.
The number without context tells you nothing. CPM in context tells you everything about whether the reach was worth buying.
Frequently Asked Questions
What does mille mean in cost per mille?
Mille is the Latin word for thousand. CPM is the cost per 1,000 impressions, not per one impression. So a CPM of 200 means you pay 200 for every 1,000 times your ad is shown, or 0.20 per individual impression. The M in CPM follows the Roman numeral convention used in advertising since before digital media.
What is the difference between CPM and CPC?
CPM charges for impressions regardless of clicks. CPC charges only when someone clicks. CPM is typically used for awareness campaigns where the goal is reach and visibility. CPC is used for performance campaigns where the goal is driving traffic or conversions. The same campaign can be measured on both metrics, but optimising for one usually means accepting a trade-off on the other.
What is a good CPM?
It depends entirely on the channel, the audience and the objective. LinkedIn CPMs are among the highest in digital advertising because the audience is professional and hard to reach elsewhere. Display CPMs can be very low but also very ineffective. The more relevant measure is cost per result: how much did each thousand impressions actually cost you in sales or leads? CPM is only a good metric when reach itself is the goal.