Free tool
CPM and CPC calculator
The short answer
CPM is spend per 1,000 impressions, CPC is spend per click, and CTR links them: CPC = CPM / (1,000 x CTR). $1,200 for 150,000 impressions and 1,800 clicks is an $8 CPM, a $0.67 CPC and a 1.2% CTR. Use the converter to compare a CPM-priced placement with a CPC-priced one on the same footing.
On this page 6 sections
CPM, CPC and CTR
From a campaign report
Converter: CPM and CTR to effective CPC
CPM
$8.00
CPC
$0.67
CTR
1.20%
Effective CPC (converter)
$1.00
CPM, CPC and CTR are linked: CPC = CPM / (1,000 x CTR). A cheap CPM with a weak CTR can cost more per click than an expensive CPM that people click.
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The formulas
- CPM = spend / impressions x 1,000.
- CPC = spend / clicks.
- CTR = clicks / impressions.
- Effective CPC from a CPM = CPM / (1,000 x CTR). Effective CPM from a CPC = CPC x CTR x 1,000.
Worked example
A newsletter sponsorship is sold at a $9 CPM. If readers click at 0.9%, every 1,000 impressions brings 9 clicks for $9: an effective CPC of $1.00. A search campaign at $1.40 a click looks dearer, but only if both sets of clicks convert at the same rate. Compare on CPA once conversions are tracked.
Why the numbers differ between platforms
- Impressions are counted differently. Some platforms count an impression when the ad is served, others only when it is viewable on screen. Google Ads also sells viewable CPM (vCPM), counting only impressions that could be seen.
- Clicks are not visits. Ad platforms count clicks; analytics counts sessions that loaded the tag. Consent banners, ad blockers and fast bounces mean GA4 typically shows fewer. See why GA4 numbers don't match.
- Average CPC is an average. In Google Ads it is total click cost divided by clicks; individual clicks cost more or less than that.
Track which placement produced each visit with the UTM builder, and check click-through on its own with the CTR calculator. Reporting tools that pull CPM and CPC from every ad platform into one view are compared in the best marketing reporting tools.
Questions
- How do you convert CPM to CPC?
- Divide the CPM by 1,000 times the click-through rate. A $9 CPM at a 0.9% CTR is $9 / (1,000 x 0.009) = $1.00 per click.
- What does CPM stand for?
- Cost per mille: the cost of 1,000 impressions. Mille is Latin for thousand. Google Ads calls it cost-per-thousand impressions.
- Is a lower CPM always better?
- No. A cheap CPM on a placement nobody clicks or buys from can cost more per customer than an expensive one. Compare effective CPC, then cost per conversion.
Sources
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