US marketplace. Fee figures reflect Amazon’s published 2026 rate cards, last verified August 2026. Confirm your own per-SKU figures in Seller Central’s Fee Preview report.
Contribution margin is what one unit contributes toward covering your fixed costs after every variable cost of selling that unit is paid. It is the selling price minus landed COGS, referral fee, fulfillment fee, per-unit storage, returns cost, and advertising. Your break-even point is total fixed costs divided by contribution margin per unit — the number of units you must sell before the business earns its first dollar of profit. A SKU with a $9.67 contribution margin against $1,565 of monthly fixed costs needs 162 units a month to break even. Below that, it is subsidised by your other SKUs.
Most Amazon sellers track net margin and stop there. Net margin tells you whether the business made money last month. Contribution margin tells you what will happen if you change something — raise the price, cut ad spend, drop the SKU, add a second one. It is the only margin figure that answers a forward-looking question, which is why it is the number operators use to make decisions and the number most dashboards do not show.
What is the difference between contribution margin, gross margin, and net margin?
These three are routinely used as if they were interchangeable. They answer different questions, and using the wrong one produces the wrong decision.
| Margin type | What it subtracts | Question it answers |
|---|---|---|
| Gross margin | Landed COGS only | How much markup does the product carry before selling costs? |
| Contribution margin | Landed COGS + all variable selling costs (referral, fulfillment, storage, returns, ads) | What does one more unit sold add to the business? |
| Operating margin | Everything above, plus fixed operating costs | Is the whole business profitable at current volume? |
| Net margin | Everything, including tax, interest, and one-offs | What did the owner actually keep? |
The critical boundary is between variable and fixed. A variable cost is incurred because you sold a unit. A fixed cost is incurred whether you sell one unit or ten thousand. Referral fees are variable. Your Professional selling plan subscription at $39.99 a month is fixed. Get the classification wrong and every downstream number is wrong.
Which Amazon costs are variable and which are fixed?
Amazon’s fee structure makes this messier than a standard retail P&L, because several charges look fixed but scale with volume, and others look variable but do not.
| Cost | Classification | Note |
|---|---|---|
| Landed COGS (unit cost + inbound freight + duty + prep) | Variable | Must include freight and tariffs, not just the supplier invoice |
| Referral fee (8–17%, most categories 15%) | Variable | Scales exactly with price |
| FBA fulfillment fee | Variable | Now banded by price as well as size and weight — see below |
| Fuel and logistics surcharge (3.5% of the fulfillment fee, from April 17, 2026) | Variable | Multiply the published fulfillment fee by 1.035 |
| Monthly storage | Semi-variable | Driven by inventory held, not units sold — allocate per unit using turnover |
| Returns cost (refund admin fee, sunk fulfillment fee, returns processing fee, unsellable units) | Variable | Allocate as an expected cost across all units, not only returned ones |
| Advertising | Variable in practice | Treat as variable if you would cut it when you stop selling the SKU |
| Inbound placement service fee | Variable | Avoidable at zero with Amazon-optimised splits; otherwise $0.14–$1.90 standard-size |
| Professional selling plan ($39.99/mo) | Fixed | |
| Software, VA salaries, accountant, office | Fixed | |
| Aged inventory surcharge | Fixed-ish penalty | Caused by inventory decisions, not sales — keep it out of contribution margin and treat it as a planning cost |
Advertising is the contentious one. Purists put it below contribution margin because it is discretionary. In practice, if your SKU stops ranking without ads, the ad spend is the cost of the sale and belongs above the line. Pick one treatment and apply it consistently across the catalogue — mixing treatments makes SKU comparison meaningless.
How is the fulfillment fee structured in 2026?
This matters for contribution margin because the 2026 rate card added a third dimension. Fulfillment fees are now published in three price bands — under $10, $10 to $50, and over $50 — on top of size tier and shipping weight. A product priced at $9.99 and the same product at $10.00 can carry meaningfully different fees, because items under $10 qualify automatically for Low Price FBA, worth an average $0.86 per unit.
Selected non-peak 2026 standard-size rates, before the fuel surcharge:
| Size tier | Shipping weight | Under $10 | $10–$50 | Over $50 |
|---|---|---|---|---|
| Small standard | 2 oz or less | $2.43 | $3.32 | $3.58 |
| Small standard | 14+ to 16 oz | $2.95 | $3.96 | $4.22 |
| Large standard | 4 oz or less | $2.91 | $3.73 | $3.99 |
| Large standard | 1.25+ to 1.5 lb | $4.60 | $5.42 | $5.68 |
| Large standard | 1.75+ to 2 lb | $5.00 | $5.82 | $6.08 |
| Large standard | 3+ lb to 20 lb | $6.15 + $0.08/4 oz | $6.97 + $0.08/4 oz | $7.23 + $0.08/4 oz |
Apparel and dangerous goods have their own higher schedules. Add 3.5% to any of these figures for orders fulfilled on or after April 17, 2026.
How do you calculate contribution margin per unit?
Take a standard-size supplement priced at $29.99, sourced from Asia, large standard tier at 1.25–1.5 lb. That puts it in the $10–$50 band at $5.42 base, or $5.61 with the fuel surcharge.
| Line | Amount |
|---|---|
| Selling price | $29.99 |
| Landed COGS (unit $5.10 + freight $0.85 + duty $0.60 + prep $0.35) | −$6.90 |
| Referral fee (15%) | −$4.50 |
| FBA fulfillment fee (large standard, 1.25–1.5 lb, $10–$50 band, incl. 3.5% surcharge) | −$5.61 |
| Storage, allocated per unit at 6× annual turns | −$0.31 |
| Expected returns cost (4% return rate × $7.40 cost per return) | −$0.30 |
| Advertising (TACoS 9%) | −$2.70 |
| Contribution margin per unit | $9.67 |
| Contribution margin ratio | 32.2% |
The ratio matters as much as the dollar figure. The dollar amount tells you how fast you cover fixed costs. The ratio tells you how much of every additional sales dollar survives to do that work — and it is the number that tells you how sensitive the SKU is to a price change.
How many units do you need to sell to break even?
Break-even units = total fixed costs ÷ contribution margin per unit.
Suppose your monthly fixed costs are: Professional plan $39.99, analytics and repricing software $180, VA $900, accountant $350, insurance $95. Total: $1,565.
$1,565 ÷ $9.67 = 162 units per month. Everything above 162 units is profit at $9.67 a unit.
Now run the same calculation on a second SKU — a $14.99 kitchen accessory with a $2.15 contribution margin. Break-even on the same fixed base is 728 units a month. Same fixed costs, more than four times the volume required. This is the calculation that tells you which SKU deserves inventory capital and which one is a volume trap.
What is break-even in dollars, and why does the ratio matter more at scale?
Break-even revenue = fixed costs ÷ contribution margin ratio.
For the supplement: $1,565 ÷ 0.322 = $4,854 in monthly revenue. For the kitchen accessory: $1,565 ÷ 0.143 = $10,913. The second SKU has to generate more than twice the revenue to reach the same point, which is the practical reason low-margin high-volume catalogues feel like treadmills. Every fixed-cost increase — a new software subscription, a second VA — is absorbed at the contribution margin ratio, not at the gross margin ratio the seller has in their head.
This also explains the counterintuitive result where cutting price to drive volume destroys profit. Drop the supplement from $29.99 to $26.99. The referral fee falls by $0.45 and advertising at constant TACoS falls by $0.27, but you lose $3.00 of revenue, and the fulfillment fee does not move at all because the product stays in the same weight and price band. New contribution margin: $7.39. Break-even volume rises from 162 to 212 units — a 31% volume increase required just to stand still. If the price cut does not produce at least 31% more units, the SKU is worse off.
Note what did the damage. Of the $3.00 price cut, only $0.72 came back as reduced fees. The fulfillment fee is a fixed dollar amount within its band, so discounting is far more expensive on Amazon than a percentage-fee mental model suggests.
How do you handle a SKU with negative contribution margin?
A negative contribution margin means every additional unit sold makes the business poorer. There is no volume at which it improves, because the loss scales with sales. This is the one case where the correct action is immediate: raise the price, cut the variable cost, or stop selling it.
A positive contribution margin below your average is a different situation. That SKU is still helping cover fixed costs, so removing it does not save you its share of the overhead — the overhead redistributes onto the remaining SKUs and their break-even points rise. The test for killing a low-contribution SKU is not whether it is below average; it is whether the inventory capital and warehouse space it consumes would generate more contribution somewhere else.
Common mistakes
- Using the supplier invoice as COGS. Inbound freight, duty, and prep can add 20–35% on top of the unit cost. A contribution margin calculated on invoice cost alone is systematically overstated.
- Allocating fixed costs into per-unit cost. Spreading your VA’s salary across units turns a fixed cost into a fake variable one and makes the break-even calculation circular. Fixed costs belong in the numerator, never in the per-unit figure.
- Using a single fulfillment fee across the catalogue. Since January 2026 the fee depends on price band as well as size and weight. A SKU repriced across the $10 or $50 boundary changes fee band, and the contribution margin moves without anyone touching the cost side.
- Forgetting the fuel surcharge. The 3.5% surcharge from April 17, 2026 applies to every FBA fulfillment fee. Rate cards published before that date do not include it.
- Using blended catalogue averages. A 28% average contribution margin across 40 SKUs typically hides a range from −4% to 45%. Break-even is a per-SKU calculation.
- Ignoring returns until they show up as refunds. A 4% return rate does not cost 4% of revenue. It costs the refunded amount, the sunk outbound fulfillment fee, the refund administration fee, the returns processing fee, and the unit itself if it comes back unsellable.
Keeping this current per SKU is the part sellers underestimate. It requires landed cost, current banded fee data, actual return rates, and ad spend attributed at the SKU level, all refreshed as Amazon’s rate cards move — and they moved twice in 2026 alone. Tools like sellerboard pull the fee and returns data directly from Amazon’s reports so the contribution figure reflects what was actually charged rather than what the rate card said in January.
Frequently asked questions
Is contribution margin the same as gross profit?
No. Gross profit subtracts only COGS. Contribution margin subtracts every variable cost of selling, including Amazon’s fees and your advertising. On a typical FBA SKU, gross margin might read 77% while contribution margin is 32%.
Should advertising be included in contribution margin?
Include it if the SKU depends on ads to sell. Exclude it if ads are a growth investment you could switch off without losing baseline organic sales. Whichever you choose, apply it to every SKU or the comparison breaks.
What is a good contribution margin for an Amazon seller?
It depends on your fixed-cost base and turnover, not on a benchmark. A 20% contribution margin at 12 inventory turns a year generates far more annual profit per dollar of capital than 40% at 2 turns. Judge it against break-even volume and cash cycle, not against a percentage target.
How often should I recalculate break-even?
Monthly at minimum, and immediately after any fee change, price change, supplier cost change, or new fixed cost. Adding a $200/month software subscription raises break-even by 21 units on a $9.67 contribution margin — worth knowing before you sign up.
Does break-even include the owner’s salary?
If you need the business to pay you, include your draw in fixed costs. The resulting figure is your true break-even. Excluding it produces a number that looks reachable but leaves you working unpaid.
