The one metric that actually matters

We live in a world of dashboards, attribution models, and weekly reports packed with numbers. But when it comes to measuring what’s working, most of it is noise. Here’s what I think should sit at the centre of every agency and client conversation.

Ask most marketing teams what they’re optimising for and you’ll get a range of answers. Traffic. Leads. Conversion rate. Cost per acquisition. Return on ad spend. All of them valid. All of them useful. None of them the point.

The metric that matters is profit. Not revenue. Not volume. Profit.

I know that sounds obvious, but in practice, it gets lost surprisingly quickly. You can drive a 100% increase in sales and watch your margins shrink because the cost of acquiring those customers crept up without anyone noticing. You can hit every KPI on the dashboard and still end the quarter in a worse position than you started.

This isn’t an argument against tracking the other stuff. Traffic quality, conversion rate, cost per acquisition – these all matter, and they’re all useful signals. But they’re signals pointing towards something. That something is profit. When we lose sight of that, we end up optimising the wrong things.

Working with Forbes Solicitors is a good example of what this shift looks like in practice. When we took on the account, the existing paid search campaigns were optimised for volume – as many leads as possible, as cheaply as possible. The numbers looked reasonable. But the leads themselves were poor quality, requiring extensive follow-up and rarely converting to fee-paying work. The cost per enquiry looked fine. The cost per profitable instruction was quietly damaging.

We stripped back the campaigns, cut the keywords that were driving volume without value, and rebuilt around the enquiry types that actually converted. Lead volume dropped. Profit per lead improved significantly. From a dashboard perspective, some metrics got worse. From a business perspective, the client was in a better position.

We’ve seen the same dynamic play out differently with an e-commerce client in the automotive sector. The temptation when improving average order value is to focus purely on conversion rate… get more people to buy more. We tracked revenue per user instead, a metric that balances order value against conversion rate in one number. That discipline stopped us from chasing AOV improvements that would have hurt overall revenue by reducing checkout completions. The constraint made the strategy sharper.

What profit-first thinking changes, practically, is the conversation. When both agency and client are anchored to the same commercial outcome, there’s less debate about which metric to report and more focus on what’s actually moving the business forward. The hard questions get asked earlier: which channels are generating margin, not just volume? Which customer segments are worth acquiring at current costs? Where is budget working against us?

Those conversations are sometimes uncomfortable. But they’re the right ones to have. Profit is the number that, when the books are balanced at the end of the quarter, tells you honestly whether the work was worth doing.

Start there. Work backwards. Everything else falls into place.