What PPC measures
Pay-per-click advertising charges for a click under the relevant buying model. Cost per click is a delivery measure, not a customer acquisition result. Search ads often respond to expressed intent; social ads often introduce an offer while someone is doing something else.
Before spending
Choose a specific audience or search intent, a clear offer, a matching landing page, and a useful conversion event. Verify tracking and prevent duplicate purchase events. For lead generation, define what makes a lead qualified and connect later sales outcomes where possible.
Write a bounded test
State the hypothesis, creative or keyword focus, budget cap, review date, and quality guardrail. Use negative keywords when appropriate for search, check actual search terms, and separate materially different intents. Do not change every variable at once and then claim you know what caused the result.
Understand the money
CPC = ad spend / clicks. Cost per lead = spend / leads. Cost per qualified lead = spend / qualified leads. Media-only CAC = ad spend / acquired customers; blended CAC also includes agreed sales and marketing costs. ROAS = attributed revenue / ad spend. ROAS is not profit, and attributed conversions are not automatically incremental conversions.
Illustrative economics
With $1,000 spent, 500 clicks, 20 leads, 5 qualified leads, and 2 customers, CPC is $2, CPL is $50, cost per qualified lead is $200, and media-only CAC is $500. If attributed revenue is $2,000, ROAS is 2.0x. Delivery costs, margins, refunds, labor, and retention still determine whether this is attractive.
Scale on evidence
Check conversion lag and attribution windows. A small early sample may be inconclusive. Scale only when lead quality, conversion economics, delivery capacity, and customer value justify it. Budget changes can alter who you reach and what you pay.