Quick answer: ROAS tells you revenue returned for each unit of ad spend, CPA tells you the cost of each conversion, CTR shows whether an ad earns clicks, and conversion rate shows whether those clicks become the outcome you want. Read them together before changing budget.
Use the free Marketing Metrics Calculator to calculate all six core metrics from one campaign snapshot.
The marketing metrics that belong together
| Metric | Formula | What it helps answer |
|---|---|---|
| ROAS | Revenue ÷ ad spend | How much revenue did the campaign return? |
| CPA | Ad spend ÷ conversions | What did each conversion cost? |
| CTR | Clicks ÷ impressions × 100 | Does the ad earn attention? |
| Conversion rate | Conversions ÷ clicks × 100 | Does the landing experience turn attention into action? |
| CPM | Ad spend ÷ impressions × 1,000 | What does reach cost? |
| CPC | Ad spend ÷ clicks | What does each visit cost? |
How to read the pattern, not just one number
A low CPA is not automatically good if the conversion is low value or unlikely to retain. A high CTR is not automatically good if the landing page has a weak conversion rate. ROAS can look excellent on a small retargeting audience while new-customer acquisition is losing money. The useful question is not “which number improved?” but “where did the journey change?”
- Low CTR and normal conversion rate: test the audience, offer, hook, or creative before rebuilding the page.
- High CTR and low conversion rate: check message match, landing-page speed, pricing clarity, and form friction.
- Healthy CPA and weak ROAS: check order value, refunds, gross margin, and whether the conversion definition is too loose.
- Good ROAS but little scale: inspect impression share, audience size, frequency, and marginal CPA before raising budget.
Set the tracking foundation before comparing campaigns
Metrics only work when traffic is attributed consistently. Use a shared UTM naming convention for manually tagged campaigns, and build links with the UTM Builder. This prevents the same channel appearing as several source/medium combinations in GA4.
For Google Ads, use the platform’s auto-tagging and a linked GA4 property unless your reporting design calls for a deliberate manual-tagging exception. For other paid and owned channels, define one source, one medium, and one campaign pattern before launch.
Know your break-even point
Revenue ROAS does not equal profit. If a product has a 40% contribution margin before ad spend, a 2.0x revenue ROAS may still lose money after fulfillment, payment fees, support, and returns. Calculate a break-even target with real contribution margin, then assess each campaign against that target rather than a generic industry benchmark.
For subscription or repeat-purchase businesses, add customer lifetime value to the decision. The LTV:CAC Calculator estimates LTV, LTV:CAC, and payback from revenue, margin, churn, and acquisition cost. Treat it as a starting model and validate against cohort retention data.
A weekly review routine
- Check spend, revenue, conversions, and conversion definition accuracy.
- Calculate ROAS, CPA, CTR, conversion rate, CPM, and CPC.
- Segment by campaign, audience, creative, and landing page before acting.
- Change one material variable at a time and write down the hypothesis.
- Review new-customer economics separately from retargeting and existing-customer campaigns.
Frequently asked questions
What is a good ROAS?
A good ROAS is above your own break-even threshold, not a universal multiple. Margin, repeat purchase, returns, fulfillment cost, and the campaign objective all change the answer.
What is the difference between CPA and CPC?
CPC is the cost of a click. CPA is the cost of a completed conversion. CPA includes both the cost of getting visitors and how effectively the page converts them.
Can a campaign have a high CTR and still perform poorly?
Yes. A high CTR with a low conversion rate often signals a mismatch between the ad promise and the landing-page experience, or low-intent traffic.
Should I optimize for ROAS or CPA?
Use CPA when the conversion has roughly stable value or is an early funnel action. Use ROAS when you can pass reliable revenue back to the ad platform. In either case, compare against profit economics and customer quality.