About this tool
The CPM Calculator works out cost per thousand impressions from what you spent and how many impressions the campaign delivered, and it runs the formula backward too: enter a quoted CPM and a budget to see how many impressions you can buy, or a CPM and an impression goal to see what it will cost. It is for media buyers comparing display, video, and social placements sold on impressions, for anyone reading a platform report that shows spend and impressions but not CPM, and for planners sizing a budget against a reach target. A sensitivity table shows how far the same budget stretches at CPMs from 2 to 30, and a bridge panel converts CPM into the equivalent cost per click at an expected click-through rate.
How it works
CPM = spend ÷ impressions × 1,000; the M is the Roman numeral for one thousand. Solving for spend gives spend = CPM × impressions ÷ 1,000, and solving for impressions gives impressions = spend ÷ CPM × 1,000. The bridge to click pricing uses the fact that 1,000 impressions at click-through rate CTR produce 1,000 × CTR clicks, so CPC = CPM ÷ (1,000 × CTR) and, in reverse, CPM = CPC × 1,000 × CTR. The sensitivity table applies the impressions formula to your budget at each CPM in the range. The currency symbol is display only; no exchange rates are applied.
Frequently asked questions
What does CPM stand for, and why per 1,000?
CPM is cost per mille; mille is Latin for thousand, so it is the price of 1,000 ad impressions. Per-impression prices are tiny fractions of a cent, so the industry quotes them per thousand to get readable numbers. A CPM of $4.00 means each single impression costs $0.004.
Is a lower CPM always better?
Not on its own. CPM prices exposure, not results. Cheap inventory often has lower viewability, weaker targeting, or a poorer click-through rate, so the effective cost per click or per conversion can end up higher. Use the CPM to CPC bridge on this page to compare placements on what they actually deliver.
What counts as an impression?
It depends on the platform. Most count an impression when the ad is served, some only when it renders, and viewable CPM (vCPM) counts only impressions that met a viewability standard, commonly 50% of the ad's pixels in view for at least one second for display. Compare CPMs only when they are measured the same way.
How do I convert CPM to CPC?
Divide the CPM by the number of clicks you expect from 1,000 impressions, which is 1,000 × CTR. At a $4.00 CPM and a 1% CTR you get 10 clicks per 1,000 impressions, so the effective CPC is $0.40. If the CTR drops to 0.5%, the same CPM works out to $0.80 per click.