Pick what you want to find, enter the other two figures and the answer updates as you type.
CPM means cost per mille, the price of 1,000 ad impressions. An impression is one time an ad is served, not a unique person or a click.
Ad platforms, publishers and media agencies quote prices in different ways, which makes it hard to tell whether a deal is any good. This CPM calculator puts them on a level footing: give it any two of total cost, impressions and CPM, and it works out the third along with the cost of a single view. The cost per mille pricing model is the standard for display, video, podcast and social advertising, so it is the number to compare first.
Quick answer: A CPM calculator uses CPM = cost ÷ impressions × 1,000 to find the price of 1,000 ad views. A campaign costing £2,500 for 400,000 impressions has a CPM of £6.25, and the same formula rearranges to give total cost or impressions when you know the other two figures.
In This Guide
What Is CPM?
CPM stands for cost per mille, mille being Latin for a thousand. It is what you pay each time your advert is shown 1,000 times, whether or not anyone clicks. Because single impressions cost fractions of a penny, quoting per thousand keeps the numbers readable and lets you compare a newsletter sponsorship with a programmatic display buy.
Three formulas link the figures. CPM = cost ÷ impressions × 1,000. Cost = CPM × impressions ÷ 1,000. Impressions = cost ÷ CPM × 1,000. The calculator switches between them depending on what you choose to solve for.
How to Use the CPM Calculator
Step 1: Choose What to Solve For
Select CPM to check a past campaign, Total cost to price a booking, or Impressions to see how far a fixed budget will stretch. The field you are solving for is locked and filled in automatically.
Step 2: Pick Your Currency
Choose £, $ or €. The maths is the same in every currency, so this only changes how results are shown. Keep everything in one currency when comparing quotes.
Step 3: Enter the Two Figures You Know
Use the numbers from your ads manager, insertion order or media kit. If a publisher quotes a flat fee for a slot, enter the fee as cost and their stated impressions to reveal the real CPM. To mark up media for a client, the markup calculator shows the selling price that hits your margin, so you can quote with confidence.
Step 4: Read the Results
The headline shows your answer, with the cost of one impression, impressions per unit of currency and impressions per hundred below. The box shows how a 20% rise in CPM would shrink your reach at the same spend.
Worked Example: Comparing Two Media Quotes
Tom manages marketing for a cycling accessories brand with £2,500 to spend. A cycling magazine's website offers 400,000 impressions for the full £2,500, while a podcast network offers 150,000 downloads with a host read advert for £1,200. Running both through the calculator gives a CPM of £6.25 for the website and £8.00 for the podcast.
| Option | Cost | Impressions | CPM |
|---|---|---|---|
| Magazine website banners | £2,500 | 400,000 | £6.25 |
| Podcast host read | £1,200 | 150,000 | £8.00 |
| Social video, fixed budget | £1,000 | 222,222 | £4.50 |
The cheapest CPM is not automatically the best buy. A host read in a niche podcast may hold attention far better than a banner, so look at clicks and sales as well. Once you know two options' CPMs, the percentage difference calculator tells you exactly how far apart they are, which helps when you negotiate.
For context on where UK advertisers spend their money, the IAB UK digital adspend study tracks the market twice a year, broken down by format and sector so you can see which channels are growing.
CPM Calculator Terms You Should Know
These definitions explain the media buying language used by the CPM calculator, so you can compare quotes from publishers, podcasts and social platforms fairly.
- Cost per mille
- A pricing model that charges a set amount for every 1,000 times an advert is shown. Mille is Latin for thousand, and quoting per thousand keeps prices readable when a single view costs only a fraction of a penny.
- Ad impression
- One occasion on which an advert is served to a screen or played to a listener. Platforms count impressions under slightly different rules, so check definitions before comparing CPMs across different media owners.
- Reach
- The number of different people who saw an advert at least once during a campaign. It differs from impressions, which count every showing, so a high impression total can reflect repeated views by a small audience.
- Frequency
- The average number of times each person reached by a campaign saw the advert, calculated as impressions divided by reach. Too low a frequency limits recall, while too high a frequency wastes budget and annoys viewers.
- Insertion order
- A written agreement between an advertiser and a publisher setting out what will run, where, when and at what price. It often states a guaranteed number of impressions, which makes the effective CPM easy to calculate.
- Programmatic advertising
- The automated buying and selling of advertising space through software platforms, often in real time auctions. Inventory bought this way is almost always priced on a CPM basis, which makes it simple to compare.
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How we checked this tool: the Tools Veria Editorial Team built this tool by hand, checked it against the official rules or published standards where they apply, and tested it against worked examples. Results are estimates for planning, not personal financial or tax advice. Read our editorial policy and disclaimer, or report an error.
Frequently Asked Questions
How do I calculate CPM from cost and impressions?
Divide the total cost by the number of impressions, then multiply by 1,000. £2,500 for 400,000 impressions is a CPM of £6.25.
How many impressions will £500 buy at a £5 CPM?
Divide £500 by £5 and multiply by 1,000, which gives 100,000 impressions.
What is the difference between CPM and CPC?
CPM is the price of 1,000 times your advert is shown. CPC is the price of each click, so you only pay when someone acts on the advert.
Does CPM count unique people?
No. One person seeing your advert three times counts as three impressions. Reach is the measure for unique people.
Why is my CPM higher in November and December?
More advertisers compete for the same audiences in the run up to Black Friday and Christmas, so auction prices rise across most platforms.
What does eCPM mean?
Effective CPM is the CPM you end up paying or earning when a campaign was bought another way, such as per click. It is worked out with the same formula from the final cost and impressions.