Unit economics

Revenue and costs per unit — per order, per customer or per delivery — to see whether each unit makes or loses money before fixed costs.

FormulaPer unit: commission + fees charged − variable costs

How we work it through

1
Pick the unit: an order, a cart, a customer or a delivery.
2
List every cost that grows with each unit — delivery, payment fees, discounts, returns.
3
Show which line turns the unit negative, not only the total.

On the practice dataset

The query we run on Meridian, Atterna’s practice marketplace, and what it returns.

-- per cart, delivery alone
SELECT (SUM(delivery_fee_eur)
        - (SELECT SUM(shipping_cost_eur)
           FROM meridian.parcels)) / COUNT(*)
FROM meridian.carts;

Result−€2.46 per cart on delivery; after commission, payment fees, discounts and returns a cart leaves €1.49

The common trap

Leaving out costs that grow with volume, such as delivery, payment fees or discounts.

When an AI answers

An AI assistant

“Each cart earns us €5.28 in commission.”

What it didn’t know: It saw the commission table and did not know delivery costs more than buyers pay for it.
Ask back: “After delivery, payment fees, discounts and returns, what does one cart leave?”

Paste a real AI answer into the checker — it writes these questions for you →