When a contractor compares marketing agencies, cost per lead is usually the first question asked. It's an easy number to compare, which is exactly why it becomes the main decision factor -- even though it says very little about whether that lead actually turns into a closed job.
Cost per lead legitimately varies by service type, geography, and channel. A full remodel doesn't compete for the same audience as a smaller repair job, and Meta Ads behaves differently from Google Ads in terms of search intent. Comparing two agencies on that single number without looking at what's actually being advertised is comparing different things.
A cheap lead that doesn't qualify, doesn't respond, or never had a real budget for the project isn't more profitable than a more expensive one that moves forward. What matters isn't cost per lead -- it's cost per scheduled estimate and, ultimately, cost per closed job. That's the number that actually connects to revenue.
Being able to compare on that basis requires a process that tracks what happens to every lead after the form: whether they were contacted, how fast, whether they qualified, whether they got an estimate, and whether they closed. Without that tracking, any cost-per-lead number is only half the story.
Before choosing an agency based on who promises the cheapest lead, it's worth asking how they define and track lead quality, and what happens to those leads once they're in the CRM. That question usually separates agencies selling volume from agencies selling results.