Measure PPC performance by checking five core metrics in order: Click-Through Rate (CTR), Cost Per Acquisition (CPA), Return on Ad Spend (ROAS), Quality Score, and Conversion Rate. A campaign is performing effectively when conversions arrive at or below your target CPA, ROAS exceeds your minimum profitability threshold, and CTR meets or beats the industry benchmark for your sector. No single metric tells the full story; all five must be read together.
Key facts
- A PPC campaign is effective when it delivers conversions at or below the target CPA and generates a ROAS that exceeds the minimum profitability threshold.
- CTR formula: (Clicks / Impressions) x 100. The Google Ads average CTR across all industries on Search is approximately 6.11% according to WordStream's 2026 benchmarks.
- CPA formula: Total ad spend divided by number of conversions. This is the primary pass/fail metric and should be defined before a campaign launches.
- ROAS formula: Revenue generated divided by ad spend. A ROAS of 4.0 means R4 (or $4) is returned for every R1 (or $1) spent; however, ROAS must exceed your gross margin threshold to be genuinely profitable.
- Quality Score is Google's 1-to-10 rating of keyword, ad, and landing page relevance. Scores of 7 or above indicate strong alignment and typically reduce cost per click.
- Conversion Rate formula: (Conversions / Clicks) x 100. High CTR paired with low Conversion Rate signals the landing page is failing, not the ad.
- Impression Share is the percentage of total available impressions your ads actually received. A low figure means budget constraints or a poor Quality Score is limiting reach.
The Five Core PPC Metrics and What They Tell You
Before spending a single rand on paid search, you need a clear measurement framework. The five metrics below are the foundation. Read them together rather than in isolation, because each one reveals a different layer of campaign health.
Click-Through Rate
CTR is the percentage of people who saw your ad and clicked it, calculated as (Clicks / Impressions) x 100. According to WordStream's 2026 industry benchmarks, the average CTR on Google Search across all sectors sits at approximately 6.11%. A CTR well below that figure is an early warning sign: either the ad copy is not compelling enough, or the targeting is pulling in the wrong audience. Catching a weak CTR early saves budget before it drains on irrelevant clicks.
Cost Per Acquisition
CPA is your total ad spend divided by the number of conversions. It answers the most important business question: what did it cost to win one customer or lead? Set your target CPA before the campaign goes live and treat it as the primary pass/fail measure. If actual CPA runs more than 20% above target for two consecutive weeks, the campaign needs structural attention, not just a bid tweak.
Return on Ad Spend
ROAS is revenue generated divided by ad spend. A ROAS of 4.0 means R4 returned for every R1 spent. The critical nuance most guides skip: a ROAS above 1.0 is not automatically a success. If your gross margin is 30%, a ROAS of 2.0 still leaves you losing money once product costs are factored in. Always compare ROAS against your margin threshold, not just against zero.
Quality Score
Google assigns each keyword a Quality Score from 1 to 10, based on the relevance of your keyword, ad copy, and landing page to one another. Scores of 7 or above indicate strong alignment. A higher Quality Score directly lowers your cost per click and improves ad position without requiring higher bids, making it one of the most cost-effective levers available inside the platform.
Conversion Rate and Impression Share
Conversion Rate is (Conversions / Clicks) x 100. A high CTR paired with a low Conversion Rate is a clear signal: the ad is attracting clicks, but the landing page is not delivering on the promise. Impression Share, meanwhile, tells you what percentage of available impressions your ads actually captured. A low Impression Share means budget constraints or a weak Quality Score is preventing your ads from showing as often as they could.
Tracking PPC Campaigns Correctly from Day One
Tracking must be in place before the first click is served. Setting it up after the campaign launches means the early data is lost and optimisation decisions are made on incomplete information.
- Install Google Ads conversion tracking on every goal action: form submissions, purchases, phone calls, and chat initiations.
- Import GA4 goals into Google Ads so that session-level behaviour (time on page, scroll depth) supplements click-level data.
- Add call tracking if phone leads are a meaningful part of your business model. Calls that are not tracked inflate your apparent CPA.
- Connect your ad platform to a reporting dashboard. Google Looker Studio is free and sufficient for most accounts. Third-party tools add cross-channel aggregation if you run campaigns across multiple platforms simultaneously.
- Review performance at three levels every week: account level for overall spend efficiency, campaign level to see which objective is hitting CPA targets, and ad group or keyword level to find where wasted spend is hiding.
Without this structure, CTR and CPC become vanity metrics. They look like data, but they cannot tell you whether the campaign is profitable.
Defining Success Before Launch, Not After
A campaign cannot be judged without a pre-agreed definition of success. Three inputs are required before any budget is committed:
- Target CPA: the maximum acceptable cost per conversion.
- Minimum ROAS: the revenue return that covers margin and justifies spend.
- Conversion volume goal: the number of conversions needed per month for the result to be commercially meaningful.
This last point is frequently overlooked. A campaign achieving a 500% ROAS on two conversions per month is not a scalable success; it is a statistical anomaly. Volume and efficiency must both be present.
A simple pass/fail scorecard makes weekly reviews faster and more consistent:
| Metric | Healthy Signal | Warning Signal |
|---|---|---|
| CTR (Search) | Above 5% | Below 2% |
| Quality Score | 7 or above | Below 5 |
| CPA | At or below target | More than 20% over target |
| ROAS | Above margin threshold | Below 1.5 |
| Conversion Rate | Above 3% | Below 1% |
These benchmarks are starting points. Adjust them to your sector and margin structure once you have at least 30 days of account data.
Practical Steps to Optimise a PPC Campaign
Measurement only creates value when it drives action. Once the data is in, optimisation follows a clear sequence.
- Fix the lowest Quality Score keywords first. Pause or rewrite ads for any keyword scoring below 5. Align the landing page copy to the exact search intent behind that keyword.
- Review the Search Terms report every 7 days. Wasted spend on irrelevant searches is the most common reason CPA climbs. Add negative keywords weekly, not monthly.
- Test one variable at a time. Run A/B tests on headlines, calls to action, or landing pages, but never all three simultaneously. Wait for a minimum of 100 conversions per variant before drawing conclusions.
- Apply bid modifiers by device, location, and time of day. If mobile users convert at half the rate of desktop users, reduce mobile bids accordingly. This directly reduces CPA without changing creative.
- Pause underperforming ad groups before scaling. Increasing budget on a campaign that contains weak ad groups amplifies waste. Isolate what works, then scale it.
Optimisation is not a one-time event. The accounts that perform best over 12 months are those reviewed on a fixed weekly schedule, with changes documented and tested systematically.
Connecting PPC Metrics to Broader Marketing Effectiveness
PPC metrics sit within a wider measurement picture. Once a campaign is stable, it is worth connecting click-level data to longer-term business metrics. Customer lifetime value (CLV) tells you whether the customers acquired through paid search are worth what you paid for them. Blended ROAS across all channels shows whether paid search is cannibalising organic traffic or genuinely adding incremental revenue. Revenue attribution models, particularly data-driven attribution in GA4, help allocate credit across the full path to conversion rather than giving it all to the last click.
For a deeper look at how organic and paid channels interact, see our guide to SEO and PPC working together. Understanding both sides of search visibility gives a more accurate picture of true marketing efficiency.
How Web SEM Measures PPC Performance for Clients
Web SEM, a Cape Town-based SEO and PPC agency founded in 2008, applies this measurement framework to every account it manages. The Search Terms report is reviewed weekly for every client, negative keyword lists are updated on the same cycle, and each client receives a plain-English performance summary covering CTR, CPA, ROAS, and Quality Score trends. No jargon, no vanity metrics, no hiding behind impressions when conversions are the point.
If your current PPC reporting leaves you unsure whether the campaign is actually working, Web SEM can audit your account and show you exactly where the data stands.