How to Calculate Your True Cost Per Acquisition (Most Contractors Get This Wrong)

Most contractors calculate CAC as ad spend divided by number of new customers. That formula ignores at least half the real cost. It also creates the illusion that cheap leads are always better, which is what pushes owners into shared-lead marketplaces where the true CAC is often 2–3x higher than an exclusive channel.

The naive formula also averages across all channels, which hides the fact that one channel is producing $200 CAC while another produces $900 CAC. The blended number looks fine while your marketing budget is quietly being wasted on the losing half.

True CAC = (Media Spend + Lead Purchase + Sales Labor + Tooling + Follow-Up Cost + Attribution Overhead) ÷ Won Customers.

Every line matters. Media Spend is your paid ad dollars. Lead Purchase is your PPL invoices. Sales Labor is the fully-loaded cost of the CSR and estimator time spent on leads that did not close. Tooling is your CRM, dialer, call tracking, forms, and reporting tools apportioned per lead. Follow-Up Cost is the SMS, email, and remarketing spend used to convert leads on their second, third, or fourth touch. Attribution Overhead is the small but real cost of the analyst or owner time spent reconciling all of this.

Aggregate CAC hides the truth. Break it out by channel: SEO, Google Local Services Ads, Google Ads, Meta, exclusive PPL vendor A, exclusive PPL vendor B, shared marketplaces, referrals, direct calls, past customers.

You will almost always find one or two channels doing the heavy lifting and one or two channels quietly bleeding your budget. The exercise of segmenting CAC is often the single most profitable analytical exercise a service business owner does in a given year — reallocation of spend based on real per-channel CAC frequently improves overall marketing ROI by 30–60%.

LTV ÷ CAC is the ratio that predicts whether your business survives. Most healthy service businesses run at 4:1 to 8:1. If you are under 3:1, either your CAC is too high or your retention economics are broken. If you are over 10:1, you are almost certainly under-investing in growth — you are leaving compounding revenue on the table by not spending more to acquire customers who would clearly be profitable.

Calculating LTV in home services is not as complicated as SaaS makes it sound. For most trades: Average Job Value × Gross Margin × Average Repeat Jobs per Customer × Referral Multiplier = LTV. A landscaper with a $4,000 average job, 45% margin, 3.2 repeat jobs per customer, and a 1.4x referral multiplier has an LTV of $8,064. If their CAC is $600, they run at 13:1 — they should be spending more, not less.

CAC payback is the number of months it takes for gross profit from a new customer to equal the CAC spent to acquire them. In home services, healthy payback is under 3 months for one-time-service categories and under 6 months for recurring-revenue models.

Long payback periods are a warning sign for cashflow-constrained businesses even when LTV:CAC looks fine. If you have to fund 9 months of CAC before recovering it, you need working capital that most small contractors do not have.

A CAC dashboard that nobody looks at is worthless. Build a simple weekly view: leads by source, cost by source, revenue by source, gross profit by source, blended CAC, and channel-level CAC. Review it every Monday. Kill or renegotiate any channel that has been over target for two consecutive months. Double budget on any channel that has been under target for two consecutive months.

The discipline of the weekly review is what turns CAC into a lever instead of a report.

The five mistakes we see most often: measuring on quoted jobs instead of closed jobs; forgetting to include follow-up conversions in the source that originated them; leaving out agency management fees; using accrual revenue instead of collected revenue for LTV; and averaging across a period long enough that seasonality distorts the picture.