Formulas
All three metrics come from the same three numbers — spend, impressions and clicks:
CTR, % = Clicks / Impressions × 100CPC = Spend / ClicksCPM = Spend / Impressions × 1,000They are also linked. If you know CPM and CTR, you can work out the expected CPC:
CPC = CPM / (CTR% × 10)The takeaway: at the same CPM, doubling CTR halves CPC. That is why creative and ad copy quality directly affect the price of a click.
Google Ads vs Meta Ads
- Google Ads (search): you usually pay per click, so CPC is the key metric. CPC is shaped by Quality Score — see 3 Quality Score levers.
- Meta Ads: most campaigns are billed on impressions, so CPM reflects the auction price and CTR reflects how engaging the creative is.
- Clicks are defined differently. In Meta, "Link clicks" count only clicks to your link, while "Clicks (all)" count every click (profile, image, reactions). Always compare the same column.
Example
The numbers are hypothetical.
- Instagram campaign: spend 500, impressions 100,000, link clicks 1,500.
- CTR = 1,500 / 100,000 × 100 = 1.5%.
- CPC = 500 / 1,500 ≈ 0.33.
- CPM = 500 / 100,000 × 1,000 = 5.
In plan mode: a budget of 1,000, expected CPM of 4 and CTR of 2% → 250,000 impressions, 5,000 clicks, CPC = 4 / (2 × 10) = 0.20.
How to read the result
- Compare the metrics with your own past results — same platform, same objective, same period. Numbers from other industries and countries are not comparable.
- If CTR is low, check the creative, headline and audience fit. For comparing formats: Instagram creative testing.
- If CPM is rising, the audience may be too narrow, competition may have increased (holiday seasons) or the creative may be fatigued.
- Do not judge CPC on its own: a cheap click that does not convert costs more than an expensive one that does. Next step — the CPA calculator.
Common mistakes
- Reading CPM as the price of one impression. CPM is the price of a thousand.
- Confusing CTR with conversion rate. CTR divides clicks by impressions, CVR divides conversions by clicks.
- Comparing different click columns — especially in Meta.
- Optimizing for CPC alone. The goal is profitable conversions, not cheap clicks.
Frequently asked questions
What is CPC?
CPC (cost per click) is the average price of a click: total spend divided by the number of clicks. 1,000 clicks for 500 means a CPC of 0.50.
What is CPM?
CPM (cost per mille) is the price of a thousand impressions: spend divided by impressions, times 1,000. It is the main price metric on impression-billed platforms such as Meta Ads.
How is CTR calculated?
CTR = clicks / impressions × 100. 300 clicks from 20,000 impressions is a CTR of 1.5%.
What is a good CTR?
There is no universal number: CTR depends on platform, format, industry and audience. The most reliable comparison is your own campaigns' past results.
How do I get CPC from CPM?
CPC = CPM / (CTR% × 10). For example, with a CPM of 5 and a CTR of 1%, CPC = 5 / 10 = 0.50.
Does the calculator store my numbers?
No. The calculation runs in your browser and nothing is sent to a server.