CPM Calculator
And Every Number Beside It
This CPM calculator turns five inputs into seven campaign numbers: cost per thousand, cost per click, click-through rate, conversion rate, cost per conversion, return on ad spend and profit.
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CPM and CPC Calculator
Seven campaign numbers, with the sums beside them
Fill in what you have. Anything left empty simply produces no number, rather than a zero that looks like a result.
- CPC
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- CTR
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- Conversion rate
- —
- Cost per conversion
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- ROAS
- —
- Profit
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Ready. Type a spend and an impression count to start.
Matching Each Metric to the Question It Answers
A campaign report opens with four or five numbers, and each one answers something different. Confusing them is how a bad campaign looks good.
CPM answers what a thousand impressions cost. CPC answers what a visit cost. Cost per conversion answers what a customer cost.
Only the third one is about money coming back. The first two are about buying attention, which is a different transaction entirely.
The cost per mille model dates to print advertising, and the arithmetic has not changed since.
The CPM Formula
Take the spend, divide it by the impressions, then times the result by 1,000. Two hundred pounds across fifty thousand impressions is a CPM of four.
The mille in the name is Latin for a thousand, which is why the number looks large next to a cost per click.
Buying on CPM means you pay for the showing rather than the visit. That suits awareness work, and it suits nothing that has to pay for itself this month.
Why A Good CPM Can Hide A Bad Campaign
Low-cost impressions are never hard to find. Buy enough of them from the wrong audience and the CPM looks excellent while nothing converts.
That is why this page shows seven numbers rather than one. CPM beside CTR beside cost per conversion tells a story that any of them alone cannot.
Check them in that same order every month. A weak CTR blames the ad or the targeting, while strong clicks with no sales blame the landing page.
ROAS Is Not Profit
Return on ad spend compares revenue with media cost. It ignores the cost of what you sold, so a ROAS of 3 on a product with a 20% margin still loses money.
Picking the Action You Count as a Conversion
Agree it before you compare anything. A sale, a qualified lead and a newsletter signup are three different events with three different values.
Most arguments about campaign performance turn out to be arguments about this definition rather than about the numbers.
Note it next to the campaign report. Then a cost per conversion of forty means something six months later, when nobody remembers what it covered.
When Your Ad Metrics Tell Different Stories
Your ad platform and your analytics will report different click counts, and neither one lies. The platform counts a click, and analytics counts a page that finished loading.
A difference of 5 to 15 per cent between the two is expected. A gap of half means something else: a slow landing page, a redirect in the way, or a tag that never fires on mobile.
Conversions disagree for a different reason. Platforms credit the click that started the journey, while analytics credits the session that finished it.
So pick one source for each decision and say which it was. Two sets of numbers in one meeting is how an hour disappears.
What To Change When A Number Looks Wrong
A low CTR points at the advert, not the bid. The audience, the image or the first three words are what somebody skipped past.
A healthy CTR with a poor conversion rate points at the page behind the click. Usually the promise in the advert is not the promise on the page.
A high cost per conversion with both of those looking fine points at the offer itself, or at the price. No CPM calculator can tell you which.
Read them in that order, and each number narrows the search for the next one.
Reading A Campaign Over A Month
A single day of figures reveals very little. Bids move, competitors join, and a Tuesday behaves nothing like a Sunday.
So read a week against the week before it, and run the CPM calculator on both, then compare the month against the same month last year.
Follow the trend more than the absolute figure. A CPC creeping up by a penny a week costs more over a quarter than any single bad day.
And write the spend beside every rate. A cheap cost per conversion on forty pounds of spend proves very little, however good it looks in a CPM calculator.
Empty Fields Stay Empty
A missing revenue figure produces no ROAS rather than a zero. Zero is a result, and a blank is a missing input, and printing one as the other is how a report starts lying.
Working With the CPM Calculator, Start to Finish
Step three is optional, and most Denwix users never need it. The results update with every figure you enter.
- 1
Enter what you have
Spend and impressions give you a CPM. Add clicks for CPC and CTR, and conversions for the cost per customer.
- 2
Add revenue if you know it
That unlocks return on ad spend and profit. Leave it out, and those two fields stay empty instead of showing a false zero.
- 3
Read the working
Each result carries its sum. Therefore you can check a number rather than taking it on trust, and paste both into a report.
- 4
Compare against yourself
Compare with the previous month too. A CPM means very little next to an industry average, and a great deal next to your own last campaign.
What Sets This CPC Calculator Apart
Most of these do one division and stop. The differences here are the number of outputs and the honesty about blanks.
Seven numbers, one form
CPM, CPC, CTR, conversion rate, cost per conversion, ROAS and profit, all from the five fields you already have.
The working shown
Every result carries its sum. A number somebody can check is worth more in a meeting than one they have to trust.
Blanks stay blank
A missing input produces a dash rather than a zero, because the two mean opposite things to anybody reading the panel.
A note that reads the numbers
A very low CTR or an impossible conversion rate gets a sentence, since those usually point at a measurement problem.
Six currencies
The symbol is yours to pick, and it only changes the display. Nothing here converts between currencies or invents a rate.
Nothing leaves your tab
Client budgets and margins pass through here. Since the arithmetic happens in your browser, none of it reaches a server.
Rules For Reading Campaign Numbers
Eight habits that stop a report being an argument.
- Define a conversion first. Write down what counts before the campaign starts. Most arguments over ad results come down to this point.
- Set the result beside your past campaigns. An industry average is built from somebody else's traffic, product and season. Your last quarter is the only fair benchmark.
- Read CTR and conversion rate in the same Denwix row. Plenty of clicks with no sales means the landing page needs work. Low clicks points at the creative or the audience.
- Put margin next to ROAS. At a 20% margin, a ROAS of 3 still loses money. The number is useful only when somebody knows what the product costs.
- Watch the impression quality. Buying cheap impressions by the million is easy. A CPM that halved overnight usually means the placements changed.
- Hold judgement on an ad until its clicks run into the hundreds. A day of data on a small budget tells you almost nothing. Wait for a few hundred clicks before drawing a conclusion.
- Save the calculation alongside the report. Six months later, nobody remembers whether spend included agency fees. The sums make that answerable.
- Note the dates covered on every report. A cost per conversion with no period beside it matches nothing else on the page. Two weeks and two months behave very differently.
- Report brand-name keywords in their own column. Brand terms convert far better and cost far less. Mixing them into one average flatters every campaign that includes them.
Six Ways Campaign Maths Misleads
Each of these produces a report that reads well and describes something that did not happen.
Rating a campaign on cost per thousand and nothing else
Cheap impressions from the wrong audience look like a win until somebody checks what converted.
Treating ROAS as profit
It ignores the cost of goods entirely. A campaign can hit a target ROAS and still lose money on every order.
Counting a click as a visit
A tenth of paid clicks never load the page. Compare the platform's clicks with your own sessions and the gap is obvious.
Averaging brand with everything else
Searches for your brand name convert many times better. Left in the average, they hide how the rest of the account is doing.
Calling three days a trend
Small budgets produce noisy numbers. A cost per conversion from forty clicks is a coin flip with a decimal point.
Excluding fees from spend
Agency and platform fees are part of what the campaign cost. Leaving them out flatters every number on this page.
Campaign Maths Questions People Ask
How does the Denwix calculator work out CPM?
Take the spend, divide it by the impressions, then times the result by 1,000. So £200 across 50,000 impressions gives a CPM of £4, and this calculator shows that sum beside the result.
How do I work out CPC?
Take the full spend and split it across every click. A cpc calculator does nothing more than that, though the useful part is seeing it beside your CTR and conversion rate.
Does a cheaper CPM always mean a better campaign?
No. Cheap impressions from an irrelevant audience are worse than expensive ones from the right people. Read CPM next to your conversion numbers.
Which click-through rate should I be happy with?
That comes down to where the ad appears. Search ads run far higher than display, so compare your own campaigns rather than a published average.
How do ROAS and ROI measure different things?
ROAS weighs the revenue against ad spend and nothing else. ROI accounts for the cost of what you sold as well, which is why the two numbers can disagree completely.
Why are some of my results blank?
Because the inputs they need are empty. A blank means "not calculated", which is different from a zero, and printing one as the other misleads.
Does the currency setting convert anything?
No. It swaps the currency sign and nothing else. Nothing here fetches an exchange rate, and a mixed-currency report needs converting before you paste it in.
Can I use this for social as well as search?
Yes. The arithmetic is the same on every platform, whatever each one calls its columns.
How many impressions do I need before the numbers settle?
A few thousand for a CTR worth reading, and a few hundred clicks before a cost per conversion means anything. Small numbers move wildly from day to day.
Should I optimise for CPC or for conversions?
Conversions, always. A cheaper click is only better when it converts at the same rate, and the cheapest clicks usually do not.
Does Denwix keep a copy of the figures I enter?
No. Your browser does every sum, so budgets and margins never reach this site, and no log records them.
Tools For A Campaign
Numbers are one part. These three cover the work around them.
Conversion Rate Calculator
Rates, targets and a comparison of two variants.
Open tool →UTM Link Builder
Tag the links so the report can group them.
Open tool →Keyword Combiner
Build the keyword list the campaign runs on.
Open tool →
Ready to Test Your Campaign Figures?
Enter what you have and read the working beside each result. The CPM calculator is free, needs no account, and keeps every figure on your device.