CPM Calculator: Cost per Thousand Impressions
Use this CPM calculator: enter ad spend and impressions to get your cost per thousand impressions.
CPM
$2.00
Enter your numbers and press Calculate.
(Total spend ÷ Impressions) × 1000
CPM formula with example
CPM = (Ad spend ÷ Impressions) × 1,000
- Take the total ad spend for the campaign, placement or audience over a set period.
- Take the number of impressions the same ads received in the same period.
- Divide spend by impressions to get the cost of one impression, then multiply by 1,000.
($300 spend ÷ 150,000 impressions) × 1,000 = $2.00 CPM
What is CPM (cost per mille)
CPM, short for cost per mille, is what you pay for one thousand ad impressions. Mille is Latin for thousand, which is where the M in CPM comes from. If a campaign spent $300 and was shown 150,000 times, its CPM is $2.00: every thousand impressions cost two dollars. The CPM meaning in marketing is the price of exposure. That makes it the natural unit for reach and brand-awareness campaigns, where being seen is the goal.
CPM is also a way of buying. In Google Ads, CPM bidding means you pay per one thousand impressions on the Google Display Network. Viewable CPM (vCPM) bidding means you only pay when your ads can be seen (Google Ads Help: Cost-per-thousand impressions). Many ad platforms also report CPM as a column for campaigns bought on other models. That lets you compare placements bought in different ways.
CPM has no view past the impression. A campaign can run at a low CPM and still perform poorly, because nothing in the formula knows whether people noticed the ad, clicked it or bought anything. Read it next to CPC and click-through rate when the goal is traffic, and next to ROAS when the goal is sales.
CPM vs CPC vs CPA: what each cost measures
CPM, CPC and CPA divide the same spend by a different event further down the funnel. The table below runs one hypothetical campaign through all three so you can see how they relate. The campaign spends $300 and gets 150,000 impressions, 600 clicks and 12 conversions.
| Metric | Formula | Result for the example | You pay for |
|---|---|---|---|
| CPM | Spend ÷ Impressions × 1,000 | $2.00 | Being shown a thousand times |
| CPC | Spend ÷ Clicks | $0.50 | A visit |
| CPA | Spend ÷ Conversions | $25.00 | A completed action |
The three numbers are linked. CPC equals CPM divided by the clicks you get per thousand impressions. In the example 0.4% of impressions became clicks, which is 4 per thousand, and $2.00 ÷ 4 = $0.50. That is the heart of the CPM vs CPC comparison: a cheap CPM only becomes a cheap click when the click-through rate holds up. A placement at a $1.00 CPM that brings 1 click per thousand impressions gives a $1.00 CPC, twice what the example campaign pays.
The formula also runs backwards for media planning. Budget = CPM × Impressions ÷ 1,000, and Impressions = Budget ÷ CPM × 1,000. At a $2.00 CPM, a $500 budget buys about 250,000 impressions, and 1,000,000 impressions cost about $2,000.
Viewable CPM and what to check when CPM moves
An impression is counted when the ad is served, whether or not anyone could see it. Google Ads counts a display ad as viewable when at least 50% of its area is on screen for at least one second (30% for large display ads). It counts a video ad as viewable when at least 50% of it is on screen while it plays for at least two seconds (Google Ads Help: Understanding viewability and Active View). Viewable CPM divides spend by viewable impressions only, so on the same campaign it is always equal to or higher than plain CPM. When CPM changes, check these before deciding that the price of reach went up or down:
Audience and placement: narrow or high-demand audiences usually cost more per thousand impressions than broad ones.
Season: more advertisers bidding for the same inventory, for example before major shopping periods, can raise CPM with nothing else changing.
Format: video, display and native placements are priced differently, so a blended CPM moves when the mix moves.
Rising frequency: a campaign that keeps showing ads to the same people can hold a low CPM while reaching fewer new people. Check reach and frequency alongside impressions.
If a lower CPM came with a lower click-through rate or fewer conversions, the campaign may have bought cheaper but less useful impressions. Compare the change with your conversion rate and cost per click before you count it as a saving.
When to use CPM
Use this CPM calculator when buying or comparing reach: placements, audiences or formats judged on what exposure costs. It is also the right unit for negotiating directly sold inventory, where the thing being bought is the impression itself. When you plan a campaign, use it backwards to turn a budget into an expected number of impressions.
Where CPM misleads
A lower CPM can come from a cheaper audience, a weaker placement or impressions that were never on screen. It does not tell you whether the impressions reached the right people. Impressions also count every showing, so one person who sees an ad five times adds five impressions. Real reach is lower than the impression count suggests.
Guides on this topic
Frequently Asked Questions
What is CPM?
CPM, or cost per mille, is the cost of one thousand ad impressions. Mille means thousand in Latin. It is calculated by dividing ad spend by impressions and multiplying by 1,000. CPM is both a metric and a way of buying: with CPM pricing you pay for impressions whether or not anyone clicks. It is the standard price unit for reach and awareness campaigns. In Google Ads it appears as CPM bidding on the Display Network.
How do you calculate CPM?
Here is how to calculate CPM: divide total ad spend by the number of impressions, then multiply by 1,000. CPM = (Spend ÷ Impressions) × 1,000. A campaign that spent $300 for 150,000 impressions has a CPM of (300 ÷ 150,000) × 1,000 = $2.00. Skipping the × 1,000 step gives the cost of a single impression, $0.002, a number too small to compare easily. When combining campaigns, add up spend and impressions first and divide once.
How is CPM different from CPC and CPA?
All three divide spend by something. CPM divides by impressions (per thousand), CPC by clicks and CPA by conversions such as orders or signups. Each step down the funnel has fewer events, so the cost per event rises. In the example on this page, the same $300 gives a $2.00 CPM, a $0.50 CPC and a $25.00 CPA. Use CPM to price reach, CPC to price visits and CPA to price results. The CPC calculator covers the middle step.
What is a good CPM?
There is no universal good CPM. Prices vary by platform, country, audience, ad format and season. A narrow audience can cost more per thousand impressions than a broad one and still be the better buy. Judge CPM against what the impressions produce. If two placements bring the same click-through rate, the cheaper CPM wins. If the cheaper one brings far fewer clicks, its cost per click can end up higher. Benchmark against your own history on the same platform and audience.
How many impressions does a budget buy at a given CPM?
Divide the budget by the CPM and multiply by 1,000. At a $2.00 CPM, a $500 budget buys about 500 ÷ 2 × 1,000 = 250,000 impressions. To find the budget for a target number of impressions, multiply CPM by impressions and divide by 1,000: 1,000,000 impressions at a $2.00 CPM cost about $2,000. Treat the result as an estimate, because the actual CPM in an auction changes with demand while the campaign runs.
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