Free tool
Cost per impression calculator
This cost per impression calculator works out your CPM, the cost per thousand impressions, from what you spent and the impressions you got. It can also work backwards to a budget or an impression count, and shows what that CPM means in clicks and conversions.
CPM (cost per 1,000 impressions)
$2.00
CPM = $500.00 ÷ 250,000 × 1,000 = $2.00
- Cost per impression
- $0.002
- Impressions per $1
- 500
- Budget
- $500.00
What it buys
- Clicks
- Cost per click
- Conversions
- Cost per conversion
- People reached
- Cost per 1,000 people
Method
How to calculate cost per impression
Calculating cost per impression takes one division: what you spent, divided by the number of impressions. Because a single impression usually costs a fraction of a cent, ad platforms quote the price per thousand impressions instead. That is CPM.
Cost per impression = total cost ÷ impressions
CPM = total cost ÷ impressions × 1,000
A worked example
A campaign spends $500 and gets 250,000 impressions. The cost per impression is $500 ÷ 250,000 = $0.002. The CPM is $0.002 × 1,000 = $2.00. Those are the calculator’s default numbers in US dollars, so you can check them above.
Working backwards
- Budget = CPM × impressions ÷ 1,000. At a $2.00 CPM, 1,000,000 impressions cost $2,000.
- Impressions = budget ÷ CPM × 1,000. A $1,200 budget at an $8.00 CPM buys 150,000 impressions.
The per thousand price
Cost per thousand calculator: why ads are priced per 1,000
The M in CPM stands for mille, Latin for thousand. Prices per impression are too small to read comfortably, so a $0.002 impression becomes a $2.00 CPM. Cost per thousand, cost per mille and CPM all mean the same thing.
Publishers use the same maths the other way round. Effective CPM, or eCPM, is earnings ÷ impressions × 1,000. Enter your earnings as the cost above to get it.
Comparing prices
CPM or CPC: which is cheaper?
A CPM tells you what attention costs. What it is worth depends on how many people click. At a click-through rate of 0.8%, every 1,000 impressions bring 8 clicks, so a $2.00 CPM works out to $0.25 per click.
Cost per click = CPM ÷ (click-through rate % × 10)
To compare a CPC offer, turn it into a CPM: CPC × click-through rate % × 10. A $0.40 CPC at 0.8% is $0.40 × 8 = $3.20 per 1,000 impressions, so at that click-through rate the $2.00 CPM is the cheaper way to buy. If your ads are clicked less often than you expect, the answer can flip, which is why the calculator lets you change the rate.
Price drivers
What pushes a CPM up or down
- Audience. Narrow or high-value audiences cost more to reach than broad ones.
- Placement and format. Video and prominent placements usually cost more than small display slots.
- Competition and season. More advertisers bidding for the same people raises the price, which is why rates often climb before big shopping periods.
- Ad quality. Platforms that auction ad space, such as Google and Meta, factor in quality or expected engagement, so weak ads can cost more per impression.
- Location. The same audience costs different amounts in different countries.
Paid impressions stop the day the budget does. Organic search keeps bringing visitors after the work is paid for, which is why the two are worth comparing. The SEO ROI calculator does the same kind of maths for organic traffic.
FAQ
Questions about cost per impression
What is cost per impression?
It is what you pay each time your ad is shown once. It is total cost divided by impressions, and it is usually a fraction of a cent, which is why prices are normally quoted as CPM, the cost per thousand impressions.
Is CPM the same as cost per impression?
They measure the same thing at different scales. CPM is the cost of 1,000 impressions, so it is 1,000 times the cost of a single impression. Be careful with the abbreviation CPI, which in app marketing usually means cost per install rather than cost per impression.
What does the M in CPM stand for?
Mille, the Latin word for thousand. CPM means cost per mille, the same as cost per thousand impressions.
How do you calculate CPM from CPC?
Multiply the cost per click by the click-through rate, then by 10 if the rate is a percentage. A $0.40 CPC at a 0.8% click-through rate equals a $3.20 CPM.
What is a good CPM?
There is no universal figure, because CPMs vary by platform, audience, format, country and season. A better test is what the CPM turns into: work out the cost per click and cost per conversion it implies, and compare those with what a result is worth to you.
Is this cost per impression calculator free?
Yes. There is no sign-up, it runs in your browser and nothing you enter is saved.
Paying for every visitor?
If most of your traffic comes from ads, book a 30 minute call. I will look at what organic search could add and what it would cost to get there.