CPM, CPC, CTR, CPA, ROAS: How to Read Ad Numbers

Definitions, formulas and a full worked example: how to read ad metrics, spot what is stuck and tell whether a campaign is profitable.

Published on September 30, 2026 · Strategy

CPM is the cost per thousand impressions, CPC the cost per click, CTR the share of people who click after seeing the ad, CPA the cost of each action you get (a sale, a lead) and ROAS what each dollar spent brings back. The first three tell you whether the ad attracts attention; the last two tell you whether it is profitable. Here are the definitions, the formulas and a full worked example to learn how to read them.

If you have never launched a campaign, start with our guide Meta Ads for beginners: your first campaign, step by step. This article is for making sense of the results table once the campaign is running, on Meta or anywhere else.

Which numbers should you look at, and in what order?

An ad reads like a funnel. People see it (impressions), some click (clicks), some of those act (conversions), and those actions bring in money (revenue). Each metric measures one stage of the funnel:

The useful reading goes bottom-up: first check whether the campaign is profitable (ROAS, CPA), then work your way up the funnel to find the stage that is stuck.

What is CPM?

CPM (cost per mille, or cost per thousand impressions) tells you how much you pay for your ad to be shown a thousand times. According to Meta's help center, it is calculated as your cost divided by the number of impressions, multiplied by 1,000.

Formula: CPM = spend ÷ impressions × 1,000.

CPM mostly reflects competition for your audience: a highly sought-after audience, the holiday season or a crowded industry push it up. On its own, it says nothing about the quality of your ad. Also, don't confuse impressions with people: the same person can see the ad several times, which is what frequency measures (impressions ÷ reach).

What is CTR?

CTR (click-through rate) is the share of impressions that lead to a click. Meta distinguishes two versions: CTR (link click-through rate), which only counts clicks that lead to the destination (your site, your form), and CTR (all), which counts every click, including on the Page name, reactions or expanding the image.

Formula: CTR = clicks ÷ impressions × 100.

To judge an ad meant to drive traffic, look at link CTR: it tells you whether the hook and creative make people want to go further. A low CTR points to the creative, the copy or the audience.

What is CPC?

CPC (cost per click) is what each click costs on average. Again, Meta offers CPC (cost per link click), which is more useful than the all-clicks version.

Formula: CPC = spend ÷ clicks.

CPC combines the two previous stages: it drops when CPM drops or when CTR rises. That is why a better creative often lowers the cost of traffic for the same budget.

What is CPA, or cost per result?

CPA (cost per action, or cost per acquisition) is what each desired action costs: a purchase, a completed form, a booking. In Ads Manager, Meta shows it as cost per result, the "result" being the action tied to the campaign objective.

Formula: CPA = spend ÷ number of actions.

To know whether a CPA is good, compare it to what an action is worth to you. A lead that turns into a customer one time in five, on a sale that leaves $200 of margin, is worth at most $40: above that, every lead costs more than it brings in.

What is ROAS?

ROAS (return on ad spend) measures the revenue generated by each dollar of advertising. Meta defines it in its help article on return on ad spend as your conversion value divided by your cost.

Formula: ROAS = revenue attributed to the ad ÷ spend.

A ROAS of 3 means $1 of advertising produced $3 of sales. That is not profit: you still have to pay for the products, shipping and fees. ROAS also assumes sales are measured, which means the Meta Pixel is installed on your site.

A full example, number by number

Fictional example: the figures below are made up to illustrate the math. They are neither averages nor targets.

Maison Sirop, a fictional small-batch syrup brand that sells online, runs a Sales campaign for two weeks. Ads Manager shows:

• Spend: $300
• Impressions: 60,000
• Link clicks: 900
• Purchases: 18
• Purchase revenue: $810

The math:

Is the campaign profitable? It depends on margin. If Maison Sirop keeps 50% of the sale price once products and shipping are paid for, $810 of sales leaves $405 of margin against $300 of ads: the campaign nets $105. At a 30% margin, it would leave only $243, and lose money.

Remember this: the minimum ROAS to avoid losing money equals 1 divided by your margin rate. With a 50% margin you need a ROAS of at least 2; with 25%, at least 4. That number, calculated for your business, is your benchmark, not an average you found online.

How do you find what is stuck?

• High CPM, decent CTR: people like the ad, but the audience is contested. Broaden the audience or let Meta choose placements.
• Low CTR: the creative or hook doesn't stop the scroll. Test another creative before touching the budget.
• Good CTR, few conversions: the problem is after the click. A slow page, an offer that doesn't match the promise, a form that is too long.
• Decent CPA, low ROAS: people buy, but small baskets. Work on the offer (bundles, free shipping above a threshold).
• Rising frequency and falling CTR: the same audience sees the same ad too often. Refresh the creatives.

Which traps should you avoid when reading these numbers?

1. Comparing to "industry averages". CPM and CTR vary by country, industry, season, format and audience. Compare your campaigns to each other, and to your break-even point.
2. Judging too early. During the learning phase, costs swing a lot. Wait for enough volume before drawing conclusions.
3. Forgetting the attribution window. A sale is credited to the ad based on a rule (for example a set number of days after the click). Two tools that don't use the same rule won't show the same numbers.
4. Mixing up CTR (all) and link CTR. The first is always higher and flatters the campaign.
5. Looking at ROAS without margin. A ROAS of 2.7 can be excellent or ruinous.

These metrics aren't specific to Meta: you will find them on Google Ads, TikTok and newer platforms like ChatGPT, compared in our article ChatGPT Ads vs. Google Ads. If you are still deciding what kind of spend fits, revisit the difference between boosting a post and running an ad. And to connect paid numbers with your organic plan, our one-hour content strategy guide helps you set goals first.

Where does Oposto fit in?

Oposto doesn't manage your campaigns or buy ads on your behalf. It works upstream and alongside: it learns your brand from your website, generates the posts, carousels and short videos that feed your social accounts, publishes them on schedule once you approve them, and measures the real performance of your posts so it can reuse what works. That way you can spot the content worth putting budget behind. The Pro plan adds ad advice and analysis to help you read your numbers.

To produce content people want to click, try Oposto for free, no credit card required.

Frequently asked questions

What is the difference between CPC and CPM?

CPM is the cost per thousand times the ad is shown; CPC is the cost of each click. CPC depends on CPM and click-through rate: at the same CPM, an ad that gets more clicks has a lower CPC.

What is a good ROAS?

There is no universal good ROAS. The threshold that matters is your break-even ROAS, equal to 1 divided by your margin rate: with a 40% margin, you need a ROAS above 2.5 to make money.

Are CPA and cost per result the same thing?

In Meta Ads Manager, cost per result is the cost of the action tied to the campaign objective. When that objective is a purchase or a lead, it matches what people usually call CPA.

Why do my numbers differ between Meta and my website?

The two tools don't credit sales the same way: attribution window, tracking blocked by some browsers, sales coming from other channels. Pick one source of truth and compare your campaigns within that same source.