The PPC metrics glossary: CPC, CTR, CPA, ROAS and the rest

Paid search has its own vocabulary, and most of it is simpler than it sounds. The trick is to see the metrics as a chain: you pay for a click, a share of those clicks convert, and a share of those conversions are worth more than they cost. Here is each link, in order.

The click metrics

CPC - cost per click

What you pay each time someone clicks your ad. It is set by an auction, not a fixed price, so it moves with competition and with your Quality Score. Across all industries the average search CPC sits around $5.42, but the range is enormous - roughly $1.63 in retail up to $9.87 in legal.

CTR - click-through rate

The share of people who clicked after seeing your ad. A high CTR signals that your ad matches the search, which lifts Quality Score and pulls your CPC down. A “good” CTR is industry-dependent: 6.64% is the all-industry average, but what matters is how you compare inside your own vertical.

Quality Score

Google's 1-10 rating of how relevant your keyword, ad and landing page are. It is the lever most agencies ignore: improving it lowers the price you pay for the same position, so a structural fix here cuts cost without cutting reach.

The conversion metrics

Conversion rate

The share of clicks that take the action you care about - a purchase, a lead, a call. The all-industry average is around 8.18%, but it swings from roughly 4% in finance to over 10% in dental. This is mostly a landing-page and offer metric, not an ads metric.

CPA - cost per acquisition

CPC divided by conversion rate, in effect: what each conversion costs you. It is the number Smart Bidding optimizes toward when you set a target CPA, and the one most worth driving down with negatives and structure.

CPL - cost per lead

CPA for lead-gen businesses. Useful, but only half the picture - a cheap lead that never closes is expensive. The fix is feeding lead quality back to Google through offline-conversion import.

The metric that ties it together

ROAS - return on ad spend

Revenue divided by ad spend. A 3:1 ROAS means $3 back for every $1 in. It is the only metric that connects the auction to the bank account - but a “good” ROAS depends entirely on your margin, which is why we set the target against your numbers rather than a blanket rule. There is a whole guide on that.

Impression share

The share of available impressions you actually captured. A low impression share lost to budget means you are leaving profitable volume on the table; lost to rank means a Quality Score or bid problem. It tells you where your ceiling is.

Reading them together

No single metric is a verdict. A high CPC is fine if conversion rate and ROAS hold up; a great CTR is worthless if the landing page leaks. We score every account on all of them at once, against your industry's real benchmarks - which is the whole point of starting with the numbers.