CPM Calculator, with CPC and CPA
Work out CPM, impressions, CPC, CPA, reach and the rest of the ad funnel from whatever you know: a budget and a CPM, a target CPA and your rates, or any other mix. Then compare buying by impression, click or conversion on the same expected rates.
Press Calculate.
What this CPM calculator does differently
CPM, CPC and CPA are the same spend divided by three different counts: impressions, clicks and conversions. They are linked by two rates, click-through rate and conversion rate, so knowing one price and the two rates gives the other two. Most calculators solve one formula at a time. This one solves the whole funnel from whatever you know, and compares the three ways of buying.
| TripleDart | Elementor | This tool | |
|---|---|---|---|
| Solves | Cost, CPM or impressions | CPC or CPM | Any of eleven measures |
| Links CPM, CPC and CPA | No | No | Through CTR and conversion rate |
| Reach and frequency | No | No | Yes |
| Works back from a target CPA | No | No | Yes |
| Compares buying models | In the text | In the text | Effective cost per conversion for each |
| Flags contradictory inputs | No | No | Yes |
| Export | None | None | CSV, Markdown, share link |
Calculator pages as fetched on 1 November 2026.
The formulas, and how they connect
- CPM, cost per mille, is spend divided by impressions, times 1,000.
- CPC, cost per click, is spend divided by clicks. It is also CPM divided by 1,000 times CTR.
- CPA, cost per acquisition, is spend divided by conversions. It is also CPC divided by the conversion rate.
- Reach is impressions divided by average frequency, the number of times each person saw the ad.
Those links let the calculator run in either direction. Start from a budget and a CPM and it fills in impressions, then clicks and conversions from your rates. Start from a target CPA and your rates and it gives the CPC and CPM you can afford to pay. Every value is marked as given or calculated, and if three values you entered contradict each other by more than 1%, the calculator says which.
CPM, CPC or CPA: which costs less?
The same audience can often be bought three ways. Which is cheapest depends on the rates, not the prices. A 12 CPM is cheaper than a 1.10 CPC only if more than 1.09% of impressions are clicked; below that, paying per click wins. Paying per conversion moves both risks to the seller, so expect the seller to price that risk in.
The comparison mode turns each price into an effective cost per conversion on the same expected CTR and conversion rate, shows how many conversions the budget buys under each, and gives the rates at which the choice flips. To judge whether the resulting CPA is affordable, the ROAS calculator works out the maximum CPA from your order economics.
How to use this CPM calculator
- Enter what you knowA budget and a CPM, or a target CPA with your CTR and conversion rate, or any other combination.
- Leave the rest blankBlank fields are calculated from the others wherever the relationships allow.
- Add frequency for reachAverage impressions per person turns impressions into people reached.
- Check the flagsIf given values contradict each other, clear one and recalculate.
- Compare buying modelsEnter CPM, CPC and CPA prices with expected rates to see which costs least per conversion.
- ExportDownload CSV or Markdown, or copy a link that reopens the same numbers.