CPM calculator
CPM is cost per thousand impressions: spend divided by impressions, multiplied by 1,000. Enter any two of spend, impressions and CPM below and this fills in the third, because the useful direction is usually backwards, from a budget to the impressions it buys.
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Calculator
The formula
CPM = (spend / impressions) x 1,000
Impressions = (spend / CPM) x 1,000
The second form is the one worth memorising. Almost every creative planning question starts from a budget, not from an impression count: how many variations can this budget resolve, how fast will frequency accumulate, how long will a set last.
How to read the result
- CPM is a price, not a performance metric. A rising CPM with flat results is an auction change; a rising CPM with falling hook rate is usually your creative.
- Compare CPM only within a placement and an audience. Broad prospecting and narrow retargeting are different markets.
- The last row is the practically useful one: at roughly 2,000 impressions per variation you can read hook rate, which is the cheapest signal a creative test produces.
What people get wrong
- Treating a low CPM as a win. Cheap impressions against the wrong audience cost more per result than expensive ones against the right audience.
- Comparing CPM across placements. TikTok, Meta feed and YouTube in-stream are priced differently for structural reasons.
- Planning creative volume from spend without dividing by audience size, which is what actually sets the fatigue clock.
Frequently asked questions
How do you calculate CPM?
Divide spend by impressions and multiply by 1,000. Spending €3,500 for 291,667 impressions is a €12 CPM.
How many impressions will my budget buy?
Divide the budget by the CPM and multiply by 1,000. At a €12 CPM, €3,500 buys about 291,667 impressions.
Is a lower CPM always better?
No. CPM is the price of attention, not its value. A cheap CPM against a poorly matched audience produces a worse cost per result than an expensive one against the right audience.