How SellerMaths builds seller math

SellerMaths Methodology

This page explains how SellerMaths turns public fee rules and small-business guidance into calculator logic, pricing guidance, compare-page scope, and reusable templates.

Last updated: 2026-03-25

Fee logic last verified: 2026-03-25

Move straight to the part you want to verify.

CalculationsHow source rules become formulasSourcesWhat documents support the logicAssumptionsWhat stays fixed and whyUpdatesHow changes are reviewedLimitsWhat this method does not cover

From source document to seller result

SellerMaths is built to make the rule path visible, not to hide it inside a black box.

Source data

Platform or public guidance

Official fee pages, pricing documents, and business guidance define the raw rule set.

SellerMaths logic

Scoped page logic

SellerMaths turns those rules into formulas, assumptions, examples, and page-level scope.

Your output

A seller-facing result

You get an estimate, pricing path, or comparison that can be checked against visible assumptions.

Source note

SellerMaths prefers visible assumptions, scoped comparisons, and source-backed updates over black-box outputs. This methodology page shows the path from public rule to seller-facing result.

How calculations are built

SellerMaths tools are built from real seller workflows. Each calculator, guide, or template starts with public rules, then narrows those rules into a page-level scope that a seller can actually inspect and use.

  • Fee structures are broken into separate formula parts such as percentage fees, flat fees, caps, thresholds, subscriptions, and optional charges.
  • Pricing logic includes break-even, margin, and cost-structure decisions where the source set supports them clearly.
  • The goal is not a universal black-box output. The goal is a scoped result that matches the stated page setup.

What data sources are used

SellerMaths uses public and verifiable sources to build calculations, examples, and trust notes. Platform fee pages define the mechanics. Business guidance supports pricing, recordkeeping, and break-even logic.

  • Official platform docs support transaction fees, payout fees, listing fees, thresholds, plans, and processor pricing.
  • Public business and tax guidance supports recordkeeping, gross receipts, cost handling, and small-business pricing logic.
  • Source families are kept visible so a seller can verify where a rule came from before acting on it.

How assumptions work

Every SellerMaths page uses assumptions. Those assumptions are shown so users can see what is fixed, what is user-entered, and what is intentionally left outside the page because the source set does not support it cleanly.

  • Country scope, currency scope, seller type, plan level, and optional fees should stay visible.
  • Ads, taxes, shipping treatment, and conversion fees are labeled instead of being buried inside the result.
  • Results are estimates for decision support, not private accounting outputs or platform invoices.

How often data is reviewed and updated

Public-doc changes act as maintenance triggers. When a fee page changes, SellerMaths reviews not only the rate itself but also the thresholds, examples, assumptions, compare-page logic, and wording tied to that rule stack.

  • Core fee logic is reviewed when platform pricing pages or help docs change.
  • Country-specific changes stay tied to the country pages they affect instead of leaking into unrelated copy.
  • A good correction request includes the page URL, the exact issue, and the public source that supports the change.

Where this methodology applies

SellerMaths methodology is designed for common seller scenarios, not for every private account setup. Results still depend on country, tax treatment, payment method mix, seller status, and the exact workflow named on the page.

  • A calculator scope is defined before the formula is shown.
  • Compare pages try to hold country, currency, order value, and setup constant before declaring a winner.
  • Templates and guides carry the same business logic into repeatable decisions rather than replacing source documents.

What this methodology does not cover

SellerMaths is not a bookkeeping app, tax filing system, legal service, or private store integration. The methodology supports clearer seller decisions, but it does not replace professional advice or official platform records.

  • Local tax rules, custom contracts, negotiated rates, and private account data sit outside standard public-page logic.
  • Public platform rules can still vary by country, category, payment method, seller status, or date.
  • Official docs remain the final authority when a platform rule changes or a seller case is unusually specific.

Where to verify or go deeper

Use the trust pages when you need the source layer, and use the live tools when you want to apply the methodology to a real scenario.

  • Open Sources to inspect the public documents behind the site.
  • Use Calculators when you want to test one exact fee or payout scenario.
  • Use Guides or Templates when you want to carry the same logic into pricing decisions or repeatable worksheets.

Assumptions

  • SellerMaths pages are built from public source documents, explicit scope choices, and seller-entered inputs rather than private account integrations.
  • A methodology note can explain only the parts of the calculation that the public source set supports cleanly for the page scope.
  • Different countries, plans, currencies, payment methods, thresholds, and seller statuses can require different formulas or assumption notes.
  • SellerMaths is an educational decision-support project and not a substitute for platform invoices, tax filings, or professional advice.

FAQ

How accurate are SellerMaths calculations?

SellerMaths calculations are scoped estimates built from public rules and visible assumptions. They are designed to support seller decisions, not to replace invoices, tax filings, or private accounting records.

Where do the fee numbers come from?

Fee numbers come from official platform fee pages, pricing documents, and the public source families listed on the Sources page.

Can I rely on this for real pricing decisions?

Yes, as a decision-support layer. You should still verify country scope, tax treatment, and any platform rule that applies to your exact seller setup before making a high-stakes change.

Do I need to adjust the assumptions for my country or setup?

Often, yes. Country, seller type, payment mix, plan level, and optional fees can change the result, which is why assumptions stay visible on SellerMaths pages.

Related pages

Related tools and guides

Related pages

Related calculators

Learn more

Compare or example

Sources

Browse All CalculatorsView SourcesRead About SellerMaths