CPM Calculator: Cost Per Thousand Ads

CPM is cost per thousand impressions. It tells you how efficiently a channel delivers reach — not clicks or revenue, just eyeballs. If you are buying display, video or awareness campaigns, this is the baseline number to benchmark.

How to calculate CPM

The formula is straightforward:

CPM = (Total Cost / Total Impressions) × 1,000

Worked example: You spent $2,400 for 600,000 impressions.

CPM = (2,400 / 600,000) × 1,000 = 4.00

Your CPM is $4.00.

What to do with the result

• Benchmark by placement and creative. A $4.00 CPM for broad display might be fine; the same CPM for a niche B2B site could be a bargain.
• Trade CPM against CTR and CPC. Cheap reach with a very low CTR can yield an expensive click.
• Track CPM drift weekly. A slow rise can hide targeting or inventory changes.
• For lower-funnel campaigns, pair CPM with ROAS instead of optimizing on CPM alone.
• See all free calculators on the Tools index.
• If you are planning retention/LTV, estimate profitability with the LTV calculator.
• Read more: CTR Calculator, ROAS Calculator, LTV Calculator.

Common mistakes and when not to trust CPM

• Counting non‑viewable impressions: A low CPM with 40% viewability may be worse than a higher CPM with 90% viewability. Compare vCPM, not raw CPM.
• Mixing apples and oranges: Don’t compare short video CPMs to display banners or open‑exchange to curated PMPs without context.
• Ignoring frequency: Cheap reach with frequency 8 wastes budget; cap frequency before chasing a lower CPM.
• Geos and audiences: CPM varies by country and audience size. Segment benchmarks.
• Suspiciously cheap inventory: Bot traffic and parked domains produce pretty CPMs and no outcomes.
• Brand safety filters: Stricter filters often raise CPM but improve outcomes; evaluate total effect.

Second example: Campaign A CPM = $4.00 with 50% viewability → vCPM ≈ $8.00. Campaign B CPM = $5.50 with 90% viewability → vCPM ≈ $6.11. B is the better reach buy despite a higher sticker CPM.

Run your own numbers

Use the free CPM Calculator to compute CPM from cost and impressions — or solve for required cost or impressions at a target CPM.