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Calculate cost per thousand impressions from spend and impressions delivered.
Calculate cost per thousand impressions from spend and impressions delivered.
Enter values above and click Calculate — results will appear here with the formula explained.
CPM — cost per mille, Latin for thousand — prices advertising by eyeballs rather than actions. Dividing spend by impressions and multiplying by 1,000 yields the rate brands negotiate against in programmatic auctions and direct media buys alike. It is the oldest pricing unit in advertising, carried over from print rate cards into real-time bidding with the arithmetic unchanged.
CPM measures exposure, not effect. Cheap impressions can still be worthless if untargeted, unseen or fraudulent; premium audiences justify high CPMs when they convert. Compare CPM within a channel and pair it with CTR and conversion metrics before judging value — a $30 CPM at 2% CTR ($1.50 effective CPC) beats a $3 CPM at 0.05% CTR ($6 effective CPC) despite costing ten times more per thousand.
Programmatic CPMs clear in second-price-style auctions with floor prices: publishers set minimums, exchanges run the auction, and bid shading means winners often pay just above the second-highest bid rather than their max. Your realized average CPM therefore blends clearing prices across thousands of micro-auctions — the number here summarizes them, and day-parting or audience changes move it because the underlying auction mix moves.
Served impressions are not seen impressions. The industry viewability standard (MRC) counts display at 50% of pixels for 1 second and video for 2 seconds; typical campaigns land 60–75% viewable, meaning a $4 served CPM is really ~$5.50–$6.70 per viewable thousand (vCPM). Optimize toward viewable or completed-view buys for awareness goals, and discount any CPM comparison that mixes served and viewable denominators.
Frequency decides whether reach builds memory or annoyance. The same budget buys wide reach at frequency 2 or narrow saturation at frequency 12 — effective frequency for simple messages sits around 3–7 exposures, after which returns flatten and brand lift can reverse. Cap frequency per user per week, then judge CPM against reached humans at sane frequency, not raw impression volume.
Invalid traffic and placement quality are the silent CPM taxes. Sophisticated invalid traffic (bots, hijacked devices) inflates impression counts while converting never; buying on authorized inventory (ads.txt-verified sellers, curated PMPs) and monitoring IVT rates keeps the denominator honest. If one placement's CPM is dramatically cheaper than peers, assume the discount prices in fraud, below-fold slots or accidental clicks until proven otherwise.
Calculate cost per thousand impressions from spend and impressions delivered. Formula: CPM = (Spend ÷ Impressions) × 1000. Example: $2,400 delivering 800,000 impressions works out to $3.00 CPM — every thousand views cost three dollars, or about 333 views per dollar.
CPM — cost per mille, Latin for thousand — prices advertising by eyeballs rather than actions. Dividing spend by impressions and multiplying by 1,000 yields the rate brands negotiate against in programmatic auctions and direct media buys alike. It is the oldest pricing unit in advertising, carried over from print rate cards into real-time bidding with the arithmetic unchanged.
CPM measures exposure, not effect. Cheap impressions can still be worthless if untargeted, unseen or fraudulent; premium audiences justify high CPMs when they convert. Compare CPM within a channel and pair it with CTR and conversion metrics before judging value — a $30 CPM at 2% CTR ($1.50 effective CPC) beats a $3 CPM at 0.05% CTR ($6 effective CPC) despite costing ten times more per thousand.
Programmatic CPMs clear in second-price-style auctions with floor prices: publishers set minimums, exchanges run the auction, and bid shading means winners often pay just above the second-highest bid rather than their max. Your realized average CPM therefore blends clearing prices across thousands of micro-auctions — the number here summarizes them, and day-parting or audience changes move it because the underlying auction mix moves.
Served impressions are not seen impressions. The industry viewability standard (MRC) counts display at 50% of pixels for 1 second and video for 2 seconds; typical campaigns land 60–75% viewable, meaning a $4 served CPM is really ~$5.50–$6.70 per viewable thousand (vCPM). Optimize toward viewable or completed-view buys for awareness goals, and discount any CPM comparison that mixes served and viewable denominators.
Frequency decides whether reach builds memory or annoyance. The same budget buys wide reach at frequency 2 or narrow saturation at frequency 12 — effective frequency for simple messages sits around 3–7 exposures, after which returns flatten and brand lift can reverse. Cap frequency per user per week, then judge CPM against reached humans at sane frequency, not raw impression volume.
Invalid traffic and placement quality are the silent CPM taxes. Sophisticated invalid traffic (bots, hijacked devices) inflates impression counts while converting never; buying on authorized inventory (ads.txt-verified sellers, curated PMPs) and monitoring IVT rates keeps the denominator honest. If one placement's CPM is dramatically cheaper than peers, assume the discount prices in fraud, below-fold slots or accidental clicks until proven otherwise.
$2,400 delivering 800,000 impressions works out to $3.00 CPM — every thousand views cost three dollars, or about 333 views per dollar. A second case: $500 for 250,000 impressions is $2.00 CPM (50,000 impressions per $100). Compare honestly: if the $3 placements run at 1% CTR ($0.30 eCPC) and the $2 ones at 0.1% ($2 eCPC), the 'expensive' inventory is nearly 7× cheaper per click.
Formulas are standard public references (see our methodology). External standards are cited in the text where they apply.
Last reviewed: September 2026 · Report an error