Google Ads Metrics Explained: CTR, CPC, Quality Score and ROAS
Read Google Ads results with confidence: CTR, CPC, conversion rate, cost per conversion, ROAS, impression share and Quality Score, with formulas and fixes.
By Mir Ullash4 min readAds
Google Ads reports a lot of numbers, but only a few decide whether your campaigns make money. This guide explains the metrics that matter, how each one is calculated, and what to do when a number looks wrong — so you can manage campaigns by results instead of guesswork.
The core metrics and formulas
| Metric | What it tells you | Formula |
|---|---|---|
| Impressions | How often your ad was shown | Counted by Google |
| CTR | How relevant and attractive the ad is for the search | Clicks ÷ Impressions × 100 |
| Avg. CPC | The average cost of a click | Cost ÷ Clicks |
| Conversion rate | How well the landing page turns clicks into leads or sales | Conversions ÷ Clicks × 100 |
| Cost / conv. | What each lead or sale costs | Cost ÷ Conversions |
| Conv. value / cost (ROAS) | Revenue for every taka spent | Conversion value ÷ Cost |
| Search impression share | How many of the eligible searches you appeared for | Impressions ÷ Eligible impressions |
| Lost IS (budget / rank) | Why you missed the rest: budget ran out, or Ad Rank was too low | Reported by Google |
A worked example
A service business spends 20,000 taka on a Search campaign. It gets 16,000 impressions, 800 clicks and 40 leads:
- CTR = 800 ÷ 16,000 × 100 = 5%
- Avg. CPC = 20,000 ÷ 800 = 25 taka
- Conversion rate = 40 ÷ 800 × 100 = 5%
- Cost per lead = 20,000 ÷ 40 = 500 taka
If one in five leads becomes a client worth 10,000 taka in profit, each lead is worth about 2,000 taka — so a 500-taka cost per lead is very healthy. Always judge cost per conversion against what a conversion is worth to you.
Quality Score: Google’s grade for your keywords
Quality Score is a 1–10 rating shown for each keyword. It’s a diagnostic, not a direct input to the auction, but it reflects the same three factors that affect your Ad Rank and cost per click:
- Expected CTR — how likely people are to click your ad for that keyword.
- Ad relevance — how closely the ad matches the intent behind the search.
- Landing page experience — how relevant, useful and fast the page is.
Each factor is rated above average, average or below average. Most practitioners treat 7–10 as healthy, 5–6 as room to improve and 1–4 as a problem. Fix the component marked below average rather than chasing the overall number.
Good vs bad signals
| Signal | What it usually means | What to do |
|---|---|---|
| Cost per conversion below what a conversion is worth | Profitable campaign | Raise budget gradually, especially if lost IS (budget) is high |
| Low CTR on a Search campaign | Ads don’t match the searches | Tighter ad groups, keywords in headlines, stronger offers, more assets |
| High CTR but low conversion rate | The ad promises something the page doesn’t deliver | Match the page to the ad, speed it up, simplify the form |
| High lost IS (budget) | Budget runs out before the day ends | Increase budget if profitable, or narrow keywords and locations |
| High lost IS (rank) | Ad Rank too low to show | Improve Quality Score and ad relevance before raising bids |
| Quality Score 1–4 | Weak relevance or landing page | Fix the component rated below average |
| Irrelevant search terms | Budget spent on the wrong searches | Add negative keywords weekly from the search terms report |
Make sure conversions are real
Every metric above depends on conversion tracking. Count only real business actions — a submitted form, a call from the ad, a purchase — and avoid counting page views as conversions. Import key events from GA4 or use the Google Ads tag, and set conversion values where you can so Smart Bidding can optimize for revenue. My GA4 setup guide covers the tracking side, and Meta Ads vs Google Ads explains how the auction works.
Frequently asked questions
What is a good CTR for Google Search ads?
+
It depends on the industry and keywords, so compare against your own campaigns over time. Search ads normally get a much higher CTR than display ads; a falling CTR usually means ads or keywords no longer match the searches.
Does Quality Score affect what I pay?
+
Quality Score itself isn’t used in the auction, but the factors behind it — expected CTR, ad relevance and landing page experience — are part of Ad Rank, so improving them usually lowers your cost per click.
What does lost impression share (budget) mean?
+
It is the share of eligible searches where your ad didn’t show because the daily budget ran out. If the campaign is profitable, raising the budget can capture those searches.
