Cost Per Mille (CPM)
CPM is the cost to serve 1,000 ad impressions, reflecting both audience demand and creative quality score from the platform.
Definition
Cost per mille (CPM), from the Latin 'mille' meaning thousand, is the price an advertiser pays for 1,000 impressions of their ad. It is the fundamental unit of media buying cost and the denominator in most efficiency calculations.
CPM is not purely a market price, it's co-determined by creative quality. Platforms like Meta and TikTok run ad auctions where both bid and predicted engagement influence who wins the impression. A creative with high predicted CTR and engagement will win auctions at a lower effective CPM than a creative with poor predicted engagement bidding the same amount. This means creative quality directly reduces your media costs.
CPM fluctuates with audience size, competition, seasonality (Q4 CPMs spike 40–80% industry-wide), and placement. Understanding your CPM trend is essential for isolating whether a cost increase is driven by market conditions or creative quality decline.
Why it matters
CPM is the cost foundation of all downstream efficiency metrics. If CPM doubles, your CPI and CPA double unless CTR and CVR improve proportionally. Creative teams that produce high-engagement ads earn lower CPMs, effectively subsidizing their UA spend. Monitoring CPM alongside engagement metrics reveals whether cost increases are market-driven (unavoidable) or creative-driven (fixable).
Formula
CPM = (Total Ad Spend ÷ Impressions) × 1,000
Example
In practice
Two campaigns target the same audience at the same bid. Campaign A uses a weak static creative and achieves $18 CPM. Campaign B uses a UGC video and achieves $11 CPM, a 39% cost advantage driven entirely by creative quality.
Frequently asked questions
What is a typical CPM for mobile apps?
Meta CPMs for app install campaigns typically range $8–$20 for mobile gaming and $12–$30 for DTC/subscription apps. TikTok generally runs $6–$15. Q4 holiday season adds 40–80% to these baselines across all platforms.
Does creative quality affect CPM?
Yes, on Meta and TikTok especially. Both platforms factor predicted engagement into their auction algorithm. Creatives with higher predicted CTR and engagement win impressions at lower CPMs. Strong creative is a direct cost-reduction tool.
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