Method

How the calculators and guides are built

SellerTools Hub uses contribution models because they keep the variable costs attached to an order visible. The result is a screening and reconciliation workflow, not a replacement for accounting records.

Core definitions

Net sales are merchandise revenue after seller-funded discounts and before costs. Contribution before ads subtracts product, fulfillment, variable platform or payment costs and expected return loss. Contribution after ads also subtracts acquisition cost. Margin divides the relevant contribution by net sales.

Input hierarchy

1. Use settled account data when it is available.
2. Use supplier invoices and shipping records for landed cost.
3. Use current platform documentation for fee rules.
4. Label forecasts and default values as estimates.
5. Never treat an unknown cost as zero because it is difficult to measure.

Scenario method

A single estimate can hide risk, so the calculators are designed for at least two passes. The expected case uses the current plan. The downside case raises one or more uncertain costs, such as acquisition, refunds or fulfillment. A decision is stronger when it survives both cases and the sensitive input is clearly identified.

Worked examples

Examples show the arithmetic from input to output and are not claimed store results. A useful example lists every cost line, states the assumption and shows which change would alter the decision. Readers should replace those values with invoices, payouts and campaign reports before acting.

Source policy

Stable mathematical concepts can be explained directly. Time-sensitive platform details link to a primary source such as a help center, seller policy page or account tool. A review date records when a page was checked; it does not imply that a fee will remain unchanged.

Limitations

The calculators do not automatically cover tax, currency conversion, chargebacks, financing, fixed payroll or every category-specific rule. Reconcile results against payouts and obtain professional advice for accounting, tax, legal or compliance decisions.