The trap

Using an average margin for all your entrants can feel instinctively accurate. Take total revenue, subtract total costs, divide by the number of runners, and you have your profit per head. Simple, right?

The problem is that the cost of one more runner isn't the same as the cost of the average runner. Some of your costs are fixed (venue, infrastructure, staff), and they exist whether 500 people cross the start line or 2,000. Adding one more runner doesn't change them.

So the average margin isn't the useful number. What matters is what that extra runner really costs you.

In practice

Take a 10K with 2,000 runners and a $50 entry fee. That's $100,000 in revenue. In this hypothetical, total costs are $80,000, leaving a $20,000 surplus. That makes the cost per runner $40 and each runner worth $10 in profit. If a marketing channel delivers 200 runners at that rate, the return is $2,000.

Does the marketing cost justify that? It's close, and maybe not.

Now look at it differently. The variable cost of one more runner (medal, T-shirt, bib, timing chip, food, insurance) comes to around $16 in this example. Your numbers may vary, but the logic still works:

$50 entry fee, minus $16 variable costs = $34 incremental margin.

Say you spend $1,500 promoting your event on Find a Race (or any marketing channel), and it brings in those same 200 runners. That works out to $7.50 in marketing cost per runner.

That means you're actually generating $26.50 in profit per runner.

That's $16.50 more per runner than the average margin model suggests. Across 200 runners, your net return on that $1,500 marketing spend goes from $500 to $5,300. Suddenly, the channel that looked like a marginal call becomes an obvious one.

The question that follows

Once you start looking at marketing this way, the question changes from "can I afford this channel?" to "is this channel helping new people find my event?"

That's where it gets interesting. Our data shows that more than 96% of bookings generated through Find a Race come from runners who have never booked a race with that organizer before. These are truly incremental bookings, not people who would have found you anyway.

Why this matters

Of course, this logic works in our favor, and we won't pretend otherwise. But it applies to every marketing decision you make.

If you're measuring marketing spend against average margin rather than incremental return, you're likely undervaluing your marketing and leaving entries on the table.