Most small businesses spend money on digital marketing and have a rough sense of whether it's working. Rough isn't good enough. If you can't point to specific numbers and trace them back to specific activities, you're making budget decisions based on gut feel — and that's expensive.
Measuring marketing ROI properly isn't complicated. It requires three things: knowing what a customer is worth, tracking where leads are coming from, and comparing cost-per-lead across your channels. That's it. Everything else is detail.
Before you can calculate ROI, you need to know what you're paying per channel. Google Ads pricing varies wildly by industry — a solicitor paying $45 per click in a competitive city is doing a completely different ROI calculation than a local plumber paying $6. Your baseline has to reflect your actual costs, not industry averages.
Start With Customer Lifetime Value
ROI only makes sense in relation to what a customer is worth. If your average client spends $3,000 with you once, that's your starting number. If they come back twice a year for three years on average, that's $18,000 in lifetime value.
With that number in hand, you can work backward. If you're willing to spend 20% of LTV to acquire a customer, your maximum acceptable customer acquisition cost is $600 (one-off) or $3,600 (repeat). Any channel that keeps you under that number is profitable. Any channel above it needs fixing or cutting.
Most businesses have never done this calculation. Once you do it, every marketing decision becomes clearer.