Why ROAS 300% Can Still Mean Losses — Gross Margin in 5 Ecommerce Verticals

"ROAS 300%, so we're profitable." I've seen this line in dozens of internal EC reports — and in maybe half of them, the business was actually losing cash. The trap is gross margin. For a 30%-margin product, ROAS 300% is barely above breakeven. Same ROAS, different margin, opposite conclusion.

This post walks through why ROAS alone is a misleading profitability signal, what gross margin actually is, where typical EC verticals land (15–75%), and the 3-step method I use to measure it from real data.

TL;DR

1. Gross margin = (revenue − COGS) ÷ revenue × 100. Business decisions run on gross profit, not revenue


2. EC gross margins span 15–75% by vertical (cosmetics 60–75%, electronics 15–25%)


3. Breakeven revenue = fixed costs ÷ gross margin. Double the margin and required revenue is halved


4. Breakeven ROAS = 1 ÷ gross margin × 100. Judging profitability on ROAS alone is dangerous


5. Measure your own gross margin in 3 steps — define COGS, take a sales-weighted average, validate against industry benchmarks

1. Why ROAS Without Gross Margin Is Misleading

ROAS 300% means "$3 of revenue per $1 of ad spend." That's revenue, not profit. Plug in different gross margins and the conclusion flips.

• 30% margin → gross profit of $0.90 against $1.00 ad spend = a $0.10 loss per $1 ad


• 50% margin → gross profit of $1.50 against $1.00 ad spend = a $0.50 profit per $1 ad


• 70% margin → gross profit of $2.10 against $1.00 ad spend = a $1.10 profit per $1 ad

The same ROAS produces three different business outcomes depending on the underlying gross margin. Reading ROAS in isolation is the most common source of overspending on ads in low-margin verticals.

2. What Gross Margin Actually Is

Gross margin shows how many cents of every revenue dollar remain as gross profit, after subtracting the cost of goods sold.

Gross margin (%) = (revenue − COGS) ÷ revenue × 100

For EC, the standard COGS bucket includes purchase cost of goods (or manufacturing cost), inbound shipping, direct packaging materials, and payment processing fees. SG&A (ad spend, payroll, fulfillment outsourcing, office rent) sits outside gross margin — it goes into operating margin further downstream. The most common mistake is dumping ad spend into COGS, which artificially depresses gross margin.

3. Five EC Vertical Benchmarks

EC gross margins span 15–75% across verticals. The product structure is fundamentally different even though everything gets labeled "ecommerce."

Pricing is the fastest lever. A 3% price increase with constant unit volume adds 3 percentage points directly to margin. Even with some churn, price elasticity above −1.0 (demand doesn't drop sharply on price increases) makes the lift net-positive on total gross profit.

Product mix moves the sales-weighted average margin by lifting the share of high-margin SKUs. Cross-sell flows that attach a high-margin item, subscriptions anchored on high-margin repeat goods, and bundles built around the higher-margin SKU are the standard plays.

COGS negotiation sits on the supplier side — unit-price negotiation, fulfillment efficiency, packaging optimization. The effect is slow, capped by supplier relationships, and best run on an annual review cycle. Bigger purchase lots trade margin against inventory risk, so this is only sensible once AOV and repeat rate are stable.

6. Measuring Your Gross Margin in 3 Steps

The formula is simple, but producing your own number and running operations against it is separate work. A 3-step method to get a current number into operations.

Step 1 — Define COGS

Fix the COGS bucket internally to the four standard items (purchase cost + inbound shipping + direct packaging + payment fees). SG&A stays out.

Step 2 — Take a sales-weighted average across SKUs

With multiple SKUs, compute the per-SKU margin and weight by revenue, not by unit count. Revenue weighting captures high-AOV products correctly.

Sales-weighted average margin = Σ (SKU i gross profit × SKU i revenue) ÷ Σ (SKU i revenue)

Reconcile GA4 e-commerce events (the purchase event's value parameter) against your internal sales system once a month. GA4 alone won't give you margin (COGS isn't in GA4) — the reconciliation step is the unavoidable part.

Step 3 — Validate against the industry benchmark

Compare to the §3 vertical ranges. Within ±10 percentage points is normal; bigger gaps need investigation.

• Below industry average — high purchase cost, heavy discounting, excessive inventory loss


• Above industry average — brand-led pricing, in-house manufacturing, restrained discounting

Once the gap is explainable, gross margin is locked, and breakeven revenue and breakeven ROAS fall out.

Wrap-up

Gross margin is upstream of every other profitability lever. EC verticals span 15–75%, so the same ROAS produces opposite conclusions depending on the underlying margin. Reading ROAS without anchoring to margin is the most common source of overspending in low-margin verticals.

The 3-step measurement — define COGS, weight by sales, validate against benchmarks — is the entry point. Once gross margin is locked, the rest of the financial decisions fall out almost mechanically.

How do you currently anchor your ad-budget decisions — pure ROAS, breakeven ROAS by margin, or something blended with LTV?

Originally posted on August 2025