CPM & Impressions Calculator
Solve CPM, cost or impressions from the other two, and add reach to see the frequency and what reaching one person really cost.
Solving for CPM
Cost $72,000.00
Impressions 10,000,000
Cost per thousand impressions $7.20
Cost per impression $0.0072
People reached 1,560,000
Average frequency 6.41
Cost per person reached $0.0462
The identity is cost equals CPM times impressions over a thousand, so
any two of the three give the other. Here $7.20 per thousand and
10,000,000 impressions come to $72,000.00, which is $0.0072 an
impression. The thousand in the middle of it is the whole reason CPM is
quoted that way: a price this small rounds to a cent, and a cent is not
the price.
You bought 10,000,000 impressions against 1,560,000 people, so each
person saw it 6.41 times and reaching one of them cost $0.0462, not
$0.0072. A plan approved on CPM and judged on reach is being measured
against a number it was not bought on.
A frequency above five is heavy. Past the first few showings the extra
ones buy less and less, and at some point they irritate. If reach is the
goal, more frequency is the expensive way to fail at it.
A CPM is only comparable to another CPM at the same viewability
standard. An impression counted when the ad is requested and an
impression counted when half the pixels are in view for a second are
different goods at the same price.
Output is valid and updates as you type.
Fix the highlighted fields to update the output.
Three numbers, one identity: cost equals CPM times impressions divided by a thousand. Media planning spends most of its time rearranging it, so this takes any two and gives you the third instead of making you move a decimal point three places and hope.
Then it does the part that matters more. CPM buys impressions, and impressions are showings rather than people. Add your reach and it tells you the frequency and what reaching one person actually cost, which is usually several times the number the plan was signed off on.
How to use
- Pick what you are solving for: CPM, cost or impressions.
- Fill in the other two. The field you are solving for is ignored.
- Optionally add the reach for the frequency and the cost per person.
Example
72,000 of media against 10,000,000 impressions and a reach of 1,560,000 people:
Solving for CPM
Cost $72,000.00
Impressions 10,000,000
Cost per thousand impressions $7.20
Cost per impression $0.0072
People reached 1,560,000
Average frequency 6.41
Cost per person reached $0.0462The CPM is 7.20 and the cost of reaching a person is 4.62 cents, which is six and a half times the cost of an impression, because each person saw the ad six and a half times. Both numbers are correct and they answer different questions. If the brief was reach, the second one is the price you paid.
Per-impression prices are shown to four decimal places on purpose: 0.0072 rounded to cents is 0.01, which is a 39 percent error and the one thing that line exists to tell you.
Pitfalls
Frequency is where media budgets leak. Past the first few exposures, each extra one buys less, and past about ten it can actively annoy. If reach is the goal, more frequency is an expensive way to miss it, and the only way to see it is to divide impressions by reach.
Impressions are not people and not views. A served impression, a viewable impression and a completed video view are three different goods that get quoted at the same kind of price. Two CPMs are only comparable at the same standard, and the standard is in the contract rather than the number.
An impression is not an opportunity to see, either. An ad below the fold on a page nobody scrolled counts as served. Viewability standards exist because of this, and a cheap CPM at 30 percent viewability is dearer than an expensive one at 80.
CPM and CPC answer to each other. CPM equals CPC times CTR times a thousand, so a CPM that holds steady while the CPC rises means the creative is being clicked less. One event, three numbers; watching only one of them hides it.
Bought impressions and delivered impressions differ. Plan on the number in the insertion order and reconcile on the number in the report, because the gap is real and it is the gap you paid for.
Compatibility
Arithmetic in the browser: nothing is uploaded and nothing is stored. The share link carries the figures, which is useful for sending a plan check to someone who does not want a spreadsheet.
Solving for impressions from a budget and a CPM is the usual planning direction, and it is the one where the thousand goes missing: a 50,000 budget at a 7.20 CPM is 6,944,444 impressions, not 6,944. The tool refuses to solve when the two numbers it needs are not both above zero rather than printing a zero or an infinity.
Reach and frequency here are the simple average frequency, impressions over reach. Real frequency is a distribution: a few people saw it thirty times and many saw it once. If the campaign is large enough for that to matter, ask the platform for the frequency distribution rather than the average.