Most founders I talk to don’t know how many of their customers are coming through paid marketing channels vs. organic. This can really damage your business. Here’s how to figure it out.

Fundamentally, there’s two ways e-commerce businesses can acquire customers. Through paid channels like Facebook, Google, etc. Or organically–which is basically customers telling their friends about your business and then they become customers.

In most ways, organic acquisition is just better. You don’t have to pay Mark Zuckerburg anything to get more customers.

But a lot of organic customers can cloud your analysis of how your paid marketing channels are performing. When you’re calculating your CAC (customer acquisition cost), organic acquisitions average down your average CAC a lot because they are $0 acquisition cost. That means your paid CAC–the cost of acquiring a customer through your paid marketing channels–could be more than you think.

So how do you figure out how many organic customers you’re getting?

The first way is customer surveys. One type is a post checkout survey which goes to every customer asking them how they first heard about your brand. The proportion of people who say “friends and family” is one approximation of your organic acquisition rate. The response rates on this can be higher than you think–Hubble had a higher than 70% response rate.

This isn’t perfect because people often don’t remember if they saw an ad but it starts getting to an answer.

The second way is brute forcing it…by turning your ads down, or off. You usually don’t want to do this if you don’t have to; if ads are profitable, you want them on all the time. But sometimes there are things like supply constraints that cause you to turn ads down or off because you don’t want to run out of product.

A silver lining to this you can see how many customers you get when ad spend is way down. Of course, customers could still come to your site remembering ads they saw months previously but over time your acquisition numbers will asymptote towards your “true” organic acquisition rate.

A less drastic approach is turning ads off in a particular geography for some time. We sometimes did this in states that made up ~5% of the US population to observe acquisition in those states vs. other states.

Finally, there are a lot of vendors that sell marketing attribution tools that claim they can estimate organic. I’m sure some of them are good but I’d only endorse ones I’ve used and I haven’t tried many.

Marketing is messy so there’s no perfect way to figure out your organic acquisition numbers. It’s worth it to try though–potentially triangulating some of the approaches above–so you actually know how you’re getting customers.