Clicks, likes, and impressions are easy to measure and easy to celebrate. But the number that decides whether your marketing is working is client acquisition cost, or CAC: how much you spend to win one paying customer.
How to calculate it
Add up everything you spent to get customers in a period, including ad spend, agency or freelancer fees, software, and the time spent on outreach. Divide it by the number of new customers you won in that same period. If you spent $3,000 in a month and won 15 new customers, your CAC is $200.
Compare it to what a customer is worth
CAC only makes sense next to customer value. If an average customer spends $1,200 with you over the relationship, a $200 CAC is healthy. If they spend $150 once, it is a problem. Know your average order, how often customers return, and your profit margin, then make sure acquisition costs leave room for profit.
Track it by channel
A single blended CAC hides what is working. Track leads and customers by source: Google ads, Meta ads, Google Business Profile, referrals, outreach calls, and organic search. Ask every new customer how they found you, use call tracking numbers, and add UTM tags to your ad links. One channel may be winning customers at $80 while another costs $600.
Watch lead-to-customer rates
A channel with cheap leads can still have an expensive CAC if those leads rarely buy. Track how many leads become customers from each source. Often the fix is not more leads, but faster follow-up, a clearer offer, or a better sales conversation.
Review it monthly
Put CAC by channel on a simple monthly sheet. Move budget toward the channels with the best CAC compared to customer value, and fix or cut the ones that do not hold up. This turns marketing from a guessing game into a decision you can defend.