Contribution Margin

What is Contribution Margin?

Contribution margin is the revenue left after variable costs (COGS, fulfillment, payment fees), expressed as a percentage, and it sets the real ceiling on how much CAC a brand can afford, because it is the money each sale actually frees up to cover acquisition and overhead.

The formula and a worked example

Contribution margin % = (revenue − variable costs) ÷ revenue. Work an example with round, illustrative numbers. A $299/month GLP-1 program carries roughly $150 of medication, pharmacy, clinician, and payment cost per patient, so contribution margin is ($299 − $150) ÷ $299 ≈ 50%, leaving about $150 a month to repay CAC before any profit exists. That $150, not the $299 headline, is what funds acquisition, which is why LTV and CAC payback must both be built on contribution margin rather than revenue.

Why it decides what CAC you can afford

Two brands with identical ROAS can sit on opposite sides of profitability purely on margin. A supplement brand needs contribution margin above roughly 35% for a 3:1 LTV:CAC to actually survive overhead once salaries and software are paid, so the same acquisition cost that is comfortable at 50% margin is fatal at 25%. Margin is the lever that converts marketing metrics into money.

Contribution margin sets your break-even MER

The cleanest use of contribution margin is that it fixes your break-even marketing efficiency ratio (MER) directly: break-even MER = 1 ÷ contribution margin.

Contribution margin is not gross margin

The two are often confused, and the difference changes the decision. Gross margin subtracts only cost of goods, so it flatters affordability; contribution margin also strips fulfillment, shipping, payment processing, and any other cost that scales with each order, leaving the number that truly repays acquisition. A supplement brand quoting a 65% gross margin can be running a 45% contribution margin once shipping and processing come out, and it is the 45% that sets the affordable CAC. Underwrite acquisition on contribution margin, and keep fixed overhead (rent, salaries, software) on a separate line, since those are covered by pooled contribution across all orders, not by any single sale.

Why it matters for health and DTC brands

Because health catalogs mix margins (a high-margin peptide next to a thin GLP-1 bundle), a single blended contribution margin can hide loss-making offers, so it is worth tracking per offer as well as blended. The highest-leverage way to widen it is usually downstream of the ad account: negotiate COGS, raise price where the offer supports it, move to 90-day supplies and bundles that spread fixed fulfillment and payment costs, and cut refunds and failed payments that quietly erase margin. Read contribution margin next to POAS, which nets the same variable costs at the campaign level, and check your break-even against the MER calculator.

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