Unit Economics Per Product: Why Every SKU Needs Its Own P&L (2026)

Unit economics per product is the profit and loss statement for a single unit sold: price at the top, then every cost that exists because that unit shipped, ending in contribution. Built per SKU rather than as a catalogue average, it exposes the items that lose money on every order — usually low-priced, heavy, or high-return products whose fixed per-order costs swamp a thin gross margin.

Two SKUs, Same Business, Opposite Economics

The costs that do not scale with price are what separate these two. Pick-and-pack labour, shipping, and the flat portion of the payment fee are near-identical on both, so they consume a far larger share of the cheaper item.

SKU B needs almost eight units to produce the contribution of one SKU A unit, while consuming eight times the packing labour and eight shipments. On a shared warehouse and a shared ad budget, it is the more expensive product to sell despite being the cheaper product to make.

Building a Unit P&L

1. Start from net price after typical discount, not list price — the average selling price is what actually arrives.
2. Add landed product cost: supplier invoice, inbound freight, duty, and a shrinkage allowance.
3. Add fulfilment: packaging, pick and pack labour at your real hourly cost, and outbound shipping at the rate you actually pay including surcharges.
4. Add transaction costs: card fees as a percentage plus the flat per-transaction charge, and marketplace commission if applicable.
5. Add a returns reserve equal to the return rate multiplied by the net cost of a return, including inbound freight and any unsellable units.
6. Add customer acquisition cost per unit, calculated as channel spend divided by units sold through that channel.

                SKU B: price $34, all costs except advertising = $23.99
Contribution before advertising: $10.01 per unit
Maximum ad spend per unit before contribution hits zero: $10.01
Actual ad spend: $6.20, leaving $3.81 of headroom
Required conversion at a $1.55 cost per click: 1 sale per 6.5 clicks
Free shipping on a single unit removes $6.90, leaving $3.11 of contribution
Free shipping above 2 units: shipping $8.40 across 2 units = $4.20 each
Two-unit order contribution: ($34.00 - $19.49) x 2 = $29.02
              

The two-unit line is the strategic conclusion. SKU B is only viable in multiples, which makes minimum order quantity and bundling a pricing decision rather than a marketing preference.

Per-Order Costs Are Not Per-Unit Costs

Where the Fee Lines Come From

Payment costs are worth modelling precisely because they are structural rather than negotiable at small scale. Debit card interchange is capped for large issuers under Regulation II, which the Federal Reserve administers, while credit card interchange is not — so payment mix changes your cost per order even when your processor rate card does not. Ask your processor for an interchange-level statement and use your actual blended effective rate in the model rather than the headline percentage.

Rebuild the unit P&L whenever shipping rates, supplier prices, or return rates move. Each of those three moves several times a year, and each one shifts contribution on the thinnest SKUs first.