What does CPM stand for?
Cost per mille. Mille is Latin for thousand, which is why the abbreviation has an M where you might expect a T. It is the cost of a thousand impressions.
CPM Calculator
What a thousand impressions costs, or what a budget buys. Fill in two of the three and the third is worked out.
Fill in any two of spend, impressions and CPM. The third is worked out, and you can go in whichever direction your question runs.
Everything here is worked out in your browser. Nothing you type is sent anywhere, and there is no account to make.
Leave this blank to work it out. Fill it in and leave one of the others blank to go the other way.
%
Optional. Turns the impressions into clicks and a cost per click.
Result
The numbers below are an example so the tool opens working. Replace them with yours.
How the number is worked out
- CPM is a price for attention, not for a result. Two placements at the same CPM can be worth very different amounts, because what they cost per click and per order depends on who saw them.
- A low CPM is a signal worth reading rather than a win. Cheap impressions usually mean a broad audience or a weak placement, and both of those show up later as a worse clickthrough rate.
What comes out
You will see
- CPM, the price of a thousand impressions
- Whichever of the three you left blank, worked out from the other two
- The cost of one single impression, for comparing against a cost per click
- Clicks at a clickthrough rate you supply, when you supply one
- The cost per click those numbers imply
- A warning when all three values are entered and they do not agree
How to use it
Three steps, and the third one is the point
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Enter the two you know
Spend and impressions if you are reading a report. CPM and spend if you are planning a buy and want to know the reach.
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Leave the one you are asking about blank
The blank field is the question. This is why the tool works in three directions instead of one.
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Add a clickthrough rate if you have one
It turns the impressions into clicks and gives you a cost per click, which is the figure a CPM is usually about to be compared against.
What CPM measures, and what it does not
CPM is cost per mille, which is Latin for thousand and the reason the abbreviation looks wrong. It is what you pay for a thousand impressions: spend divided by impressions, multiplied by a thousand.
It prices attention rather than a result. An impression is a chance to be seen, and nothing in the number says whether anybody looked, clicked or bought. That is why a CPM on its own cannot tell you whether a placement was good.
The useful version of the question is what the impressions did next, which is why the clickthrough field is here and why the result carries a cost per click when you give it one.
Why a low CPM is a signal rather than a win
Impressions get cheaper as the audience gets broader, and a broader audience is made of people less likely to care. So a falling CPM often means the delivery moved somewhere less valuable rather than that the buying got smarter.
The place this shows up is the cost per click, one line down. Halve the CPM and quarter the clickthrough rate, and the click got more expensive while the headline number got better.
That is the comparison this tool is built to make easy. Put your own rate in and the cheaper CPM has to survive a second number before you can call it cheaper.
The tool
What this one does
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Solves in three directions
Leave spend, impressions or CPM blank and the tool works out that one. The blank field is your question.
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Checks three entered values against each other
Fill in all three and it compares them. If they disagree by more than one percent it says so instead of quietly picking a winner.
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Shows the single impression price
CPM divided by a thousand, at four decimal places, because at two it rounds to nothing and stops being readable.
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Turns impressions into clicks
Give it a clickthrough rate and it multiplies rather than forecasts. The result is a consequence of your own numbers, not a prediction about them.
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Gives the implied cost per click
The figure that decides whether a cheap CPM was cheap. It appears as soon as there is a rate to work with.
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Refuses to guess
One value is not enough and the tool says which fields it needs rather than filling the gaps with a default.
Reading the result
What each line is telling you
- CPM
- The price of a thousand impressions. Comparable across placements only when the audience is comparable, which it usually is not.
- Cost per single impression
- The same figure at a scale you can hold against a cost per click. If a click costs four hundred times an impression, four hundred people ignored it.
- Clicks at that rate
- Arithmetic on the rate you entered. Change the rate and this changes; it does not know anything about your creative.
- Implied cost per click
- This is the number to compare between placements. A CPM comparison that ignores it compares prices without comparing what was bought.
A free tool answers one question.
A search audit answers the rest.
We look at your search visibility across Google and the answer engines, and tell you what is costing you orders. No charge for the first look.
In practice
What you can do with it
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Price a media buy before you commit
Enter the CPM you were quoted and your budget, and see the reach. Then add a realistic rate and see the clicks.
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Compare two placements honestly
Run each one and compare the cost per click rather than the CPM. The cheaper CPM loses this comparison more often than people expect.
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Work backwards from a reach target
Enter the impressions you need and the CPM you can get, and the spend falls out.
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Sanity check a report
Enter all three columns from a platform report. If the tool says they disagree, one of the three is measured over a different window.
Questions
CPM Calculator questions
What is a good CPM?
There is no useful answer without the audience. A narrow, high intent audience costs several times a broad one, and it is usually worth it. Compare the cost per click or the cost per order instead.
Is a lower CPM always better?
No, and this is the most common mistake in a media report. Impressions get cheaper as the audience gets broader, and a broader audience clicks less. Check what happened to the cost per click before calling a lower CPM a saving.
How is CPM different from CPC?
CPM prices being seen and CPC prices being clicked. You can convert between them if you know the clickthrough rate, which is exactly what the optional field here does.
Can I use this to plan a budget?
Yes. Enter the CPM you expect and the impressions you want, and leave spend blank. The answer is only as good as the CPM estimate you put in.
Is my data sent anywhere?
No. Everything is worked out in your browser, with no account and nothing uploaded.
The rest of the set
Fifteen more, all free, all in the browser
- CTR Calculator Clickthrough rate from clicks and impressions, or the impressions a target needs.
- Conversion Rate Calculator Conversion rate from visitors and conversions, with revenue per visitor beside it.
- ROAS Calculator Return on ad spend, the ACoS behind it, and whether your margin leaves any profit.
- CPC Calculator What one click costs, and what it costs by the time it becomes an order.
- CPA Calculator Cost per acquisition from media spend, and the ceiling your margin allows.
- CAC Calculator What winning a customer really costs, including the parts a platform cannot see.
- ARR Calculator Annual recurring revenue, with the net new figure that shows the direction.
- AOV Calculator Average order value, and what a target is worth against the same order count.
- Cost Per Lead Calculator What an enquiry costs, and what it costs once the unqualified half is priced in.
- llms.txt Generator Build an llms.txt file that tells AI crawlers which pages on your store matter.
- LTV Calculator Work out what a customer is worth over time, so you know what you can pay to win one.
- Schema Markup Generator Generate the JSON-LD a product, article or FAQ page needs, ready to paste.
- Break-even ROAS Find the return on ad spend where a campaign stops costing you money.
- CRO ROI Calculator See what a conversion rate change is worth against the traffic you already have.
- Hreflang Generator Produce the hreflang tags a multi-country store needs, without the usual mistakes.
CPM prices attention, not outcomes. A campaign can win on cost per thousand impressions and still lose everything that happens after the impression, so treat it as a diagnostic rather than a goal.
Where this comes up