How CPC and CPM are calculated
CPC (cost per click) and CPM (cost per mille, Latin for thousand) are the two most common ways digital ads are priced and reported. Both are simple ratios of what you spent to what the campaign delivered — CPC ties spend to clicks, CPM ties spend to impressions (ad views). This calculator takes the same three raw numbers from your campaign report — total spend, total impressions, and total clicks — and derives both metrics plus the click-through rate that links them.
The formulas
CPC = Total Spend ÷ Total Clicks — the average amount paid for each click, however many impressions it took to earn it.
CPM = (Total Spend ÷ Total Impressions) × 1,000 — the cost to have the ad shown 1,000 times, regardless of how many of those views turned into clicks.
CTR = (Total Clicks ÷ Total Impressions) × 100 — click-through rate, the share of impressions that resulted in a click. It is the bridge between the two cost metrics: CPM = CPC × CTR × 10, so for a fixed CPM a higher CTR implies a lower CPC, and for a fixed CPC a higher CTR implies a higher CPM.
Worked example
With the calculator's defaults — $5,000 spend, 2,000,000 impressions, and 25,000 clicks — CPC works out to $5,000 ÷ 25,000 = $0.20 per click, and CPM works out to ($5,000 ÷ 2,000,000) × 1,000 = $2.50 per 1,000 impressions. CTR is 25,000 ÷ 2,000,000 × 100 = 1.25%, meaning it takes about 80 impressions on average to produce one click.
CPC versus CPM: which fits a given campaign
CPC pricing (or bidding) ties cost directly to engagement — you only pay when someone clicks, which suits campaigns focused on traffic, leads, or sales. CPM pricing ties cost to reach and exposure — you pay for views whether or not anyone clicks, which suits brand-awareness campaigns where impressions themselves are the goal. Many ad platforms let you bid in one model while reporting results in both, which is why converting between them with the formulas above is useful even if you only ever set a CPC or CPM bid.
Reading the results together
No single metric tells the full story on its own. A low CPM with a low CTR can produce a high effective CPC, while a higher CPM with a strong CTR can still be cheap per click. Comparing CPC, CPM, and CTR side by side — rather than any one number alone — is the standard way to judge whether a campaign's pricing and audience targeting are working together.