Amazon Contribution Margin: What It Is, How to Calculate It
Contribution margin is the revenue left after all variable costs — referral fees, FBA, COGS, ads. How to calculate it for Amazon, what a healthy CM looks like, and why CM% is the only metric that matters.
Apply this to your SKUs in the 2026 P&L calculator
Run the numbers →What is contribution margin on Amazon?
Contribution margin (CM) is the amount of revenue left after subtracting all variable costs. On Amazon, the variable costs are: referral fee, FBA fulfillment fee, fuel surcharge, storage fee (per unit), COGS, and advertising spend. Fixed costs (software, subscriptions, salaries) are not part of contribution margin — they come later, in the P&L.
The formula: CM = Revenue − Referral Fee − FBA Fee − Storage/Unit − COGS − Ad Spend
Contribution margin percentage (CM%) = CM / Revenue × 100
Why CM% is the metric that matters most
Revenue is vanity. Profit is sanity. But contribution margin is the bridge. If your CM% is negative, growing revenue makes things worse — you're losing money on every unit you sell. A CM% of 0–15% is survivable for scale-stage brands but needs improvement. 20–30% is healthy for most FBA brands. Above 30% is strong.
Most Amazon brands can tell you their revenue and their ad spend. Few can tell you their contribution margin per SKU. The ones who can make better decisions.
Example: Vitamin C Serum at $24.99
Revenue: $24.99 Referral fee (15%): -$3.75 FBA fee: -$3.65 Fuel surcharge (3.5%): -$0.13 Storage (estimated/unit): -$0.18 COGS: -$4.20 Ad spend (per unit sold): -$1.13 Contribution margin: $11.95 (47.8% CM%)
This is a healthy CM%. If ads increased to $3.00/unit, CM% drops to 36.5% — still viable but tighter.
What most brands get wrong
The most common CM calculation error: not including storage cost per unit. Storage is a variable cost that scales with units held. A product sitting in FBA for 6 months has 6 months of storage cost per unit that never shows up in the per-order fee breakdown.
The second most common error: treating ad spend as a fixed overhead instead of a per-unit variable cost. If you spent $1,000 on ads and sold 500 units, your ad cost per unit is $2.00 — a variable cost that belongs in the contribution margin.
Frequently asked questions
What is a good contribution margin percentage for Amazon FBA? ▾
20–30% CM% is healthy for most FBA categories. Below 15% is risky — small fee changes or velocity drops can turn the business CM-negative. Above 35% is excellent and typically indicates strong brand differentiation or category-low competition.
Is contribution margin the same as gross margin? ▾
Similar but not identical. Gross margin typically includes COGS and sometimes some fulfillment costs. Contribution margin specifically excludes fixed costs and includes all variable costs including advertising. On Amazon, CM is the more useful metric because it captures the full per-unit economics including ads.
How often should I calculate contribution margin? ▾
Monthly at minimum, per SKU. Use the OBG calculator to see CM per SKU. Re-run every time Amazon changes fees or you change your COGS, pricing, or ad spend. Most Amazon brands should be doing this quarterly as part of financial review.