CPM Calculator (Cost per Mille)
Find your CPM (cost per mille, or cost per 1,000 impressions) from spend and impressions, see how many impressions a budget buys at a given CPM, or convert a pay-per-click price into effective CPM. It prices reach, so pair it with CTR and conversion rate before judging value.
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Formula
CPM = cost ÷ impressions × 1,000Impressions = budget ÷ CPM × 1,000Effective CPM = CPC × CTR × 1,000(CTR as a decimal, so 2% is 0.02)
Worked example
- A 500 budget that delivers 250,000 impressions: 500 ÷ 250,000 × 1,000 = 2.00 per thousand.
- A 1,000 budget at a 4.00 CPM: 1,000 ÷ 4 × 1,000 = 250,000 impressions.
- A 0.50 CPC at a 2% CTR: 0.50 × 0.02 × 1,000 = 10.00 effective CPM, so a 1,000 budget buys 100,000 impressions.
Another example
- 3,600 spent for 1,200,000 impressions: 3,600 / 1,200,000 × 1,000 = 3.00.
- A 1.20 CPC at a 1.5% CTR: 1.20 × 0.015 × 1,000 = 18.00 effective CPM. A 600 budget then buys 600 / 18 × 1,000 = 33,333 impressions.
When to use it
Use CPM to compare placements that bill differently. Turn a click price into effective CPM, or a CPM into an expected cost per click, so a display buy, a social campaign and a search campaign sit on one scale.
Rules of thumb
CPMs vary widely by platform, audience, country and season, from well under 1 on some display networks to tens of dollars for narrow business audiences. Use them to compare options within one account, not as benchmarks.
Common mistakes
- Treating a low CPM as cheap. If few people click, cost per click and per sale may be high.
- Comparing CPMs counted on different definitions of an impression.
- Dividing by 1,000 twice.
How it differs
CPM prices exposure. The cost per click calculator prices visits, the CTR calculator measures how many impressions turn into clicks, and the conversion rate calculator measures what happens after the click.
Frequently asked questions
How do you calculate CPM?
CPM is cost divided by impressions, times 1,000. A 500 budget that delivers 250,000 impressions has a CPM of 500 ÷ 250,000 × 1,000 = 2.00.
How many impressions does my budget buy?
Divide the budget by the CPM and multiply by 1,000. A 1,000 budget at a 4.00 CPM buys 1,000 ÷ 4 × 1,000 = 250,000 impressions.
What is effective CPM (eCPM)?
Effective CPM converts a pay-per-click price to a cost per 1,000 impressions: CPC × CTR × 1,000. A 0.50 CPC at a 2% CTR is 0.50 × 0.02 × 1,000 = 10.00 per thousand impressions.
Is a lower CPM always better?
No. CPM only measures the price of reach. A cheap CPM with a very low CTR or conversion rate can cost more per click or per sale than a dearer one, so compare CPC and cost per conversion too.
What is a good CPM?
It depends on the platform, audience targeting, country and time of year, so there is no universal figure. Broad display audiences are usually far cheaper than narrow business or high-income audiences. Compare CPM only against your own results, and read it next to CTR and cost per conversion.
How do I convert CPM to CPC?
Divide CPM by 1,000 times the click-through rate: CPC = CPM / (1,000 × CTR). A 4.00 CPM at a 1% CTR gives 4.00 / 10 = 0.40 per click, and at a 0.5% CTR the same CPM costs 0.80 per click.
What is the CPM formula in Excel?
Use =cost/impressions*1000. For 3,600 spent on 1,200,000 impressions, =3600/1200000*1000 gives 3.00. To find impressions from a budget use =budget/cpm*1000.