How it works
- Cost per lead = spend ÷ leads.
- Cost per booked call = spend ÷ (leads × booking rate).
- Customer acquisition cost (CAC) = spend ÷ (booked calls × close rate). This is the number that matters: a cheap lead that never books is not cheap.
- ROAS = revenue ÷ spend. It ignores what the work costs you, so it always looks better than ROI.
- ROI = (gross profit − spend) ÷ spend. Above 0% means the new customers' gross profit paid for the marketing, with some left over.
- Break-even close rate = the close rate where gross profit exactly equals spend: (spend ÷ gross profit per customer) ÷ booked calls. If your real close rate is close to it, a small slip in the office or on calls turns the channel into a loss.
Things this leaves out
- Repeat business. This counts only the first job. A customer who joins a maintenance plan, calls back for repairs, or refers a neighbor is worth more than one ticket, so a channel that looks break-even here can still be worth running.
- Overhead. Gross profit still has to cover rent, office staff, and your own pay. ROI here is marketing ROI, not net profit.
- Timing. Install leads can take weeks to close. Look at a few months together rather than one month on its own.
What published data says
LocaliQ's 2025 search ad benchmarks for home services put Air Conditioning Installation & Repair Google Ads campaigns at an average $127.74 cost per lead, and Heating & Furnaces at $129.02. Source: LocaliQ, "2025 Search Ad Benchmarks for Home Services"
ACCA's guidance on budget allocation says marketing to existing and lapsed customers returns $8–12 per dollar spent, compared to $3–4 per dollar for new-customer acquisition. Source: ACCA HVAC Blog, "Smart Spending: How to Allocate Your 2026 Marketing Budget for Maximum ROI"
More sourced numbers on lead cost and marketing budgets are in the guide HVAC Marketing Benchmarks 2026: What a Lead Should Cost You. We haven't found a solid public source for booking rates, close rates, or cost per customer by channel, so we don't quote any here. That's what the anonymous Owner Numbers survey collects, so owners can compare against real peers.
Related tools
Not sure what gross margin to enter? The markup vs margin & flat-rate price calculator shows the margin your prices actually leave. The HVAC break-even hourly rate calculator works out your real cost per billable hour, and the HVAC maintenance agreement calculator shows what a customer is worth once they join your plan. To see a customer's full lifetime value — and the most you should pay to win one — use the HVAC customer lifetime value calculator.
Losing techs? The HVAC technician turnover cost calculator adds up what one departure really costs and the raise that money could fund instead.
Setting a revenue target? The HVAC revenue goal calculator turns it into jobs and calls per day, and revenue per tech.
Paying for leads that never get answered? The HVAC missed call revenue calculator shows the jobs and revenue missed calls cost you, and what a higher booking rate is worth.
Want to see where booked calls drop off before they're sold? The HVAC sales funnel & close rate calculator shows what 5 more points of booking or closing is worth each month.
Thinking about selling one day? The HVAC business valuation calculator turns your profit and add-backs into SDE and a value range.