Cost per lead (CPL) is the metric most home builders track. It's easy to calculate — divide your monthly ad spend by the number of leads it generated — and it gives you something to optimise against. The problem is that CPL is almost completely disconnected from profitability.
The metric that actually matters is cost per acquisition (CPA) — the total cost of everything that happened between a prospect first expressing interest and a contract being signed. When builders calculate this properly for the first time, the number is usually a shock.
The CPA formula
True CPA = (Ad spend + Sales team cost allocated to lost leads + Sales overhead) ÷ Contracts signed
Let's break each component down.
1. Ad spend
This is the easy part. For a typical growth builder running Google and Meta, this is $5,000–$12,000 per month. At a blended CPL of $80–$150, that generates 50–120 raw leads per month.
2. Sales team cost allocated to lost leads
This is where most builders underestimate their true CPA. A new home sales consultant earning $90,000 base salary costs roughly $7,500/month in direct salary. Add super, tools, car allowance, and management overhead and the all-in cost is closer to $11,000–$13,000 per month per consultant.
Now ask: what percentage of that consultant's time is spent on leads that will never convert? In our experience working with volume builders, 55–65% of all inbound leads are non-viable — people who won't get finance, aren't serious, or are simply too early in their journey to take action within your sales cycle.
That means over half your sales payroll is being consumed by leads that will never sign. If your consultant's all-in cost is $12,000/month and 60% of their time goes to non-converting leads, you're effectively spending $7,200/month per consultant on work that produces nothing.
3. Sales overhead
CRM subscription, marketing automation tools, display centre costs (electricity, cleaning, part-time staff), proposal software, and the time cost of sales management. For most builders, this adds $2,000–$5,000/month across the team.
The full calculation
Here's a worked example for a builder signing 4 contracts per month:
- Ad spend: $8,000/month
- 1 sales consultant (all-in): $12,000/month
- Sales overhead: $3,000/month
- Total: $23,000/month
- Contracts signed: 4
- True CPA: $5,750 per contract
Compare that to the CPL they're likely reporting: at $100 CPL and 80 leads, they'd say their marketing cost is $100 per lead. The real number is 57× that.
The quick formula
If you want to do this calculation yourself without a full cost model:
True CPA ≈ (Monthly revenue cost per consultant × number of consultants × percentage of time on dead leads + monthly ad spend + overhead) ÷ monthly contracts
Most builders find their true CPA is somewhere between $3,500 and $8,000 per contract. On a $750,000 build at 12% gross margin, that's $90,000 gross profit — so even $8,000 CPA is comfortably viable. The issue isn't the absolute number. It's the waste hidden inside it.
Why PreQual™'s model changes the maths
PreQual™ charges 3% on contracts only. On a $750,000 build, that's $22,500. It sounds higher than a $100 CPL. But consider what changes:
- Ad spend is eliminated (PreQual™ runs the campaigns)
- Lead quality is dramatically higher — your consultant works 30 verified leads instead of 80 raw enquiries
- Sales team time on non-converting leads drops from 60% to under 20%
- The consultant who was doing 4 contracts/month can now do 6–8 from the same time investment
The $22,500 per contract cost replaces approximately $5,750 in direct costs plus the $7,200/month in wasted salary — a total saving per contract of over $10,000, before the uplift in conversion rate is factored in.
The builders who understand their true CPA are the ones who find this model compelling. The builders who only track CPL often reject it on sticker price alone.