Cost per signed case is the amount of marketing money it takes to turn a stranger into a signed client from a given channel. It's the single most honest number in law firm marketing, because it can't be inflated by traffic spikes, cheap clicks, or a pile of inquiries that never return a phone call. Either the channel produced a client, or it didn't.
It's also refreshingly easy to calculate — the difficulty is almost entirely in the bookkeeping, not the math. This guide covers the formula, how it differs from cost per lead, how to benchmark it without borrowing someone else's dubious averages, and how to lower it without spending more on leads.
The formula
Cost per signed case = total channel spend ÷ signed cases from that channel (over the same time window).
Three rules keep the number honest:
- Count all of the spend. Ad budget plus management fees, plus channel-specific subscriptions and content costs. If your paid search runs $3,000 in ads and $900 in management, the channel costs $3,900.
- Attribute cases to the channel that created them. That requires source tracking on every inquiry — tracking numbers, campaign parameters, and an intake question as backstop — carried through to the signed matter. A case whose source is "unknown" belongs in an unknown bucket, not silently credited to your favorite channel.
- Use a consistent window. Signed cases lag the marketing that produced them, sometimes by months. Rolling 90-day windows smooth the lag better than single months, especially at lower case volumes.
A quick example
Your firm spends $3,900 a month on paid search, all-in. Over 90 days that's $11,700. In the same window, nine signed matters trace back to paid search. Cost per signed case: $11,700 ÷ 9 = $1,300. Whether that's wonderful or alarming depends entirely on what those cases are worth — which is what benchmarking is about.
Cost per signed case vs. cost per lead
Cost per lead divides spend by inquiries; cost per signed case divides spend by clients. The first tells you what attention costs. The second tells you what growth costs. (For the compact definition, see the glossary entry on cost per signed case.)
| Cost per lead | Cost per signed case | |
|---|---|---|
| What it measures | Price of an inquiry | Price of a client |
| Can look great while the firm loses money | Yes — cheap, unqualified volume | No — a signed case is revenue |
| What it rewards | Volume and loose targeting | Quality, fit, and conversion |
| Data needed | Spend + inquiry counts | Spend + source-tagged case outcomes |
| Best use | Early signal within one channel | Budget decisions across channels |
The classic failure mode: a channel's cost per lead falls 30%, everyone celebrates, and three months later signed cases are flat because the new volume was noise. Cost per lead is a fine early-warning gauge inside a channel you already trust. It should never decide where the budget goes.
How to benchmark it without trusting someone else's averages
Published "average cost per case" figures are mostly self-reported, rarely say what counted as spend, and blend contingency firms with flat-fee shops as if their economics were comparable. A benchmark you can actually defend comes from your own fee structure, in two steps.
Step 1: Anchor to your average fee
Divide your expected collected fee per signed matter into what you'd tolerate paying to acquire it. Many firm owners land somewhere around 10–30% of the expected fee as a sustainable acquisition cost, with the tolerable end depending on margins, capacity, and how much repeat and referral value a client brings later. That fraction — not a survey number — is your benchmark.
Step 2: Sanity-check against your practice area's economics
The same dollar figure means opposite things in different practice areas, because the fee side differs by an order of magnitude. The bands below are illustrations of the reasoning, not industry statistics:
| Practice economics | Typical fee shape | What that implies for cost per signed case |
|---|---|---|
| High-value contingency (serious injury, medical malpractice) | Five to six figures per resolved case | Four-figure (sometimes five-figure) acquisition costs can still be very profitable — which is why competition prices these keywords accordingly |
| Volume contingency (routine auto injury) | Low five figures, high caseloads | Mid-hundreds to low four figures; volume efficiency matters as much as the headline cost |
| Retainer/hourly work (family law, business litigation) | Mid four figures and up, matters extend over time | Mid-hundreds to low four figures is often workable, more if matters run long |
| Flat-fee consumer work (estate planning, immigration, criminal defense) | Hundreds to low four figures per matter | Acquisition must stay in the low hundreds unless referrals and repeat work are counted in lifetime value |
Two habits make the benchmark useful. Track cost per signed case per channel, against your own history — the trend line and the spread between channels will tell you more than any absolute number. And revisit the fee anchor yearly; if your average matter value rises, channels you once ruled out may become affordable.
How to lower it without buying more leads
Cost per signed case has a numerator (spend) and a denominator (signed cases). Most firms only ever push on the numerator. The denominator is usually where the cheap wins are:
- Respond faster. People hiring a lawyer are often talking to several firms, and the first substantive response frequently wins. Cutting first-response time from hours to minutes raises sign-up rates without a dollar of new spend.
- Follow up more than once. A single attempt and then silence is the default at many firms. A simple multi-touch cadence over the following days recovers inquiries that were interested but busy.
- Make signing easy. Clear fee explanations at the consult and an engagement letter the client can sign the same day remove the gap where motivated clients cool off or keep shopping.
- Rebalance the source mix. Once each channel has its own cost per signed case, shift budget from the worst performer to the best. This lowers your blended cost even if no channel individually improves.
- Tighten targeting instead of expanding it. Excluding the searches, locations, and case types you don't want often lowers cost per signed case even as lead volume drops — fewer inquiries, better ones.
- Revive aged inquiries. Last quarter's unconverted consults already cost you their acquisition price. A respectful check-in costs almost nothing and every signed case from that list is nearly free.
Whatever you change, measure it: note the date, let a full window pass, and compare per-channel numbers before and after. The companion guide on measuring law firm marketing ROI shows the fuller model once you want revenue in the picture, and the free ROI calculator lets you sketch scenarios in a few minutes.
Keeping the number alive
The calculation is a division problem; the challenge is that its two inputs live in different systems — spend in ad platforms and invoices, outcomes in your practice management software. Firms solve this with a disciplined monthly spreadsheet, or with attribution software that does the join continuously — LexGrow, for instance, reports cost per signed case by channel by connecting marketing activity to the signed cases your CRM reports.
However you maintain it, the payoff is the same: marketing decisions made on the price of a client instead of the price of a click. Firms that know their cost per signed case stop paying for activity and start paying for growth — and they can tell the difference every time they open the books.