CPC, CPM, CTR, CPA and ROAS explained
Understand the advertising numbers that connect campaign spend, clicks, customers, and revenue—with worked examples.
By Adsboard · Updated November 8, 2026
CPC tells you what a click costs
Cost per click is spend divided by clicks. If an ad spends $120 and receives 60 clicks, CPC is $2. Use figures from the same date range and reporting source. A low CPC is useful only if those visitors are relevant to your business.
Try the free cost per click calculatorCPM measures the price of exposure
CPM is spend divided by impressions, multiplied by 1,000. Spending $80 for 10,000 impressions gives an $8 CPM. Impressions are displays, not unique people. Someone may see the same ad several times, so CPM does not tell you how many different people you reached.
Try the free cost per mille calculatorCTR describes the response to an impression
Click-through rate is clicks divided by impressions, multiplied by 100. With 100 clicks from 5,000 impressions, CTR is 2%. Compare like-for-like campaigns and placements. A strong CTR with weak sales can point toward a mismatch between the ad and the page or offer.
Try the free click-through rate calculatorConversion rate and CPA bring the outcome into view
If 20 of 1,000 visitors become customers, the visitor conversion rate is 2%. If acquiring those 20 customers cost $300 in advertising, CPA is $15. Define an acquisition consistently. An enquiry and a paying customer are different outcomes and should not share the same label.
Try the free cost per acquisition calculatorROAS is revenue return, not profit
Revenue of $500 from $100 of ad spend gives 5× ROAS. Revenue less advertising is $400, but product, labour, delivery, taxes, and other costs may still apply. At a 40% gross margin before advertising, the simplified break-even ROAS is 2.5×. Your business can require a higher return once fixed costs are included.
Try the free advertising roi calculator