ShiFt Answer Bank
What is the difference between cost per lead and cost per signed case?
A plain answer on the two numbers your agency and your partner each care about.
Cost per lead is your spend divided by the number of inquiries a channel produced. Cost per signed case is your spend divided by the cases that channel actually signed. They can differ by two orders of magnitude: a $75 lead can be a $7,500 signed case once you account for how few leads retain. Your agency reports cost per lead because it is easy to count. Your managing partner cares about cost per signed case because that is what pays the firm. The number in between is the one nobody reconciles.
- •Cost per lead counts inquiries; cost per signed case counts clients.
- •A worked example: 200 leads at $15,000 is $75 a lead — but 2 signed is $7,500 a case.
- •The cheapest lead source is often not the cheapest case source.
Two numbers, two audiences
Cost per lead is simple arithmetic: divide a channel’s spend by the inquiries it generated. It is the number agencies report because the ad platform hands it over automatically. Cost per signed case is harder: divide the same spend by the cases that channel actually signed. Take a channel that spent $15,000 and produced 200 leads — that is $75 per lead, a figure that looks great in a report. If only two of those leads became signed clients, the cost per signed case is $7,500. Both numbers are true. They just answer different questions, and only one of them tells you whether the channel pays for itself.
Why the cheap channel can be the expensive one
Lead volume and case quality rarely track together. A channel that floods you with cheap leads can have a terrible signed rate, while a referral or a high-intent search source produces fewer, pricier leads that sign far more often. If you allocate budget on cost per lead, you will pour money into the channel that looks efficient and starve the one that actually feeds the firm. This is the trap the two-number gap creates: the report optimizes for the metric it can see, not the one that matters. The fix is to carry the signed outcome back to the source so you can rank channels by cost per case, not cost per click.
Run your own numbers
The Cost-per-Signed-Case Calculator does this math for up to five channels on your device — spend, leads, and signed cases in; cost per lead and cost per signed case out, plus the size of the bucket you cannot yet trace. It is the fastest way to see which cheap channel is actually expensive. The Cost-per-Signed-Case pillar explains the full model behind it, including why the “unknown” bucket is the number to watch.
Questions answered
Full answers
- Which number should a law firm optimize for?
- Cost per signed case. Cost per lead measures inquiries, not clients. A channel with cheap leads can have an expensive cost per signed case, so allocating budget on cost per lead often funds the wrong source.
- How do I calculate cost per signed case?
- Divide a channel’s spend by the cases it actually signed, not the leads it produced. The Cost-per-Signed-Case Calculator does this for up to five channels and shows how much of your revenue you cannot yet trace to a source.
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