Contribution margin per channel: ranking channels honestly

Aug 22
3 min read

Updated: 2 days ago

Introduction

Channel reports rank by revenue or by conversions, and both rankings are frequently wrong about which channel is best for the business.

The channel producing the most revenue is often not the one producing the most profit, because the customers it brings cost more to acquire, cost more to serve, or buy the cheaper things.

1. Contribution margin per channel is revenue minus every cost that varies with it

Start with revenue from customers acquired through that channel. Subtract the cost of goods or delivery, then the acquisition cost, then any commission or platform fee, then payment processing.

What remains contributes toward fixed costs and profit. That figure, per channel, is the honest ranking.

Deliberately excluded: rent, salaries, insurance, software you would pay for anyway. Those do not change with the channel, so allocating them across channels adds arbitrary noise rather than information.

2. Marketplace and platform fees change the picture most

The largest surprises usually come from channels with commission attached.

A delivery platform taking a substantial percentage, a marketplace charging per sale, a booking site with a fee — each converts an apparently strong revenue channel into a thin one.

Run the calculation before concluding these channels are bad. Sometimes the contribution is small and positive on volume you would not otherwise have, which is a legitimate reason to keep it. The mistake is not knowing which situation you are in.

3. Different channels bring different baskets

The subtle effect, and the one that most often reverses a ranking.

Customers from a discount-led channel buy the discounted item and little else. Customers from a referral often buy the full-price service and add to it. The average order value and product mix differ by channel, and so does the margin on what they buy.

Which means you cannot apply a single blended margin percentage across channels. Calculate the margin on what each channel's customers actually bought.

4. Include the cost to serve, especially for services

For service businesses the delivery cost varies by customer, and channel predicts it.

Customers arriving through a price-comparison route frequently need more hand-holding, negotiate more, and take longer to close. Customers arriving by referral typically need less of all three.

Record hours per job and attribute them by channel. It is the difference between a channel that looks profitable and one that is.

5. Judge on total contribution as well as per customer

Two views, both necessary.

Contribution per customer tells you which channel produces the best customers. Total contribution tells you which channel matters most to the business.

A channel with excellent per-customer economics and five customers a year is a curiosity. One with moderate economics and volume is where the money is. Decide budget on total contribution and decide pricing and targeting on the per-customer figure.

6. Watch the marginal cost, not the average

Acquisition cost is not constant as you scale, which breaks naive reallocation.

The first customers from a channel are the cheapest. Doubling spend usually raises cost per customer, sometimes sharply, so a channel with strong contribution at current spend may be mediocre at twice the spend.

Before shifting budget into the best-ranked channel, increase it modestly and re-measure. This is the most common way a well-reasoned reallocation disappoints.

7. Recalculate quarterly, at minimum

Every input moves: platform fees change, acquisition costs rise, supplier prices change, your product mix shifts.

A quarterly recalculation is enough for most businesses. Keep the previous quarters so you can see direction, because a channel steadily losing contribution over a year is a decision you want to make early rather than suddenly.

Also recalculate after any pricing change, since that alters the margin on everything downstream.

8. Use it to decide, and record the decision

The output should be one of four actions per channel: increase, hold, reduce, or stop.

Write the action next to each channel, along with the contribution figure it was based on and the date. Next quarter, check whether the action was taken and what happened.

Without that record the analysis gets redone every quarter and acted on none of them, which is the usual fate of this kind of work. The number is easy; the follow-through is what produces the result.

Conclusion

Subtract the costs that vary with the channel — goods, acquisition, commission, processing, cost to serve — and leave fixed overhead out of the allocation entirely.

Account for the fact that channels bring different baskets and different service demands, read total contribution alongside per-customer contribution, test marginal cost before reallocating budget, recalculate quarterly, and write down the increase, hold, reduce or stop decision each time.