Principle
One money decision per page
Each calculator should answer one clear question, such as what to charge, what a platform takes, or the ad return needed to break even.
Methodology
How FeeProofed calculators are built and reviewed
FeeProofed calculators are built for sellers who need a practical money answer, not a black box. The method is simple: show the decision, show the math, let users change the assumptions, and make source-sensitive numbers easy to check.
Principle
Visible math before interpretation
The formula, inputs, worked example, and result breakdown should be visible before the page tells a seller what the number means.
Principle
Editable assumptions
Platform fees, labor, shipping, cost, margin, tax treatment, discounts, and ad spend must be easy to replace with the seller's real numbers.
Principle
Source-sensitive pages get source notes
When an outside rate affects the result, the page should point users to the official or primary source that controls the rate.
Build process
How a calculator goes from idea to page
The process keeps each page focused. If a calculator cannot explain the action, the inputs, and the formula in plain language, it is not ready for users.
Define the decision
The page starts with the action the user needs to take. If the decision is unclear, the calculator gets merged into a stronger related page.
Map the inputs
Inputs are chosen from the costs and rates that actually move the result. Optional details stay out unless they change the decision.
Show the formula
Formula lines are written plainly so a seller can audit the math without opening developer tools or trusting a black box.
Test the result
Default examples, all-zero inputs, impossible margins, fixed fees, and edge cases are checked so the calculator does not produce broken output.
Add source notes
Fee calculators and ad calculators include source notes when platform rates, definitions, or policies affect the final number.
Explain the limit
Every money tool needs a clear boundary. A calculator can estimate a decision, but it cannot know every account term, refund, tax rule, or market constraint.
Assumptions
How defaults, examples, and sources are handled
Defaults are starting points. Source notes matter when a published platform rate affects the result. Business inputs stay editable because a seller's real cost structure is the source of truth.
| Area | FeeProofed handling | User check |
|---|---|---|
| Platform fees | Use current source notes where the fee controls the math. | Confirm the account, region, payment method, and latest policy before relying on the result. |
| Business costs | Keep product cost, labor, packaging, shipping, overhead, and ad spend editable. | Replace defaults with real costs from the seller's own records. |
| Worked examples | Use simple examples that show how the formula behaves. | Treat examples as teaching numbers, not recommended prices. |
| Review notes | Flag pages when rates, formulas, or labels need another check. | Report source changes with the page URL and official source link. |
Review triggers
When a calculator should be checked again
Source-sensitive pages should not be treated as set-and-forget content. The page needs another look when a rate changes, a user reports an issue, or the structure no longer matches how sellers use the tool.
A marketplace, payment processor, or ad platform changes a published rate.
A user reports a formula issue with inputs and expected output.
A default assumption starts causing confusion.
A calculator gets a better source or clearer official definition.
A broad page can be replaced by a more useful decision-specific workflow.
Limits
What the calculators cannot decide for you
A calculator is useful because it makes assumptions visible. It still cannot replace official sources, account-specific terms, market demand, or professional judgment.
The official source controls
If a calculator and an official source disagree, use the official source and report the issue.
Your inputs control the result
A correct formula still gives a weak answer when cost, labor, shipping, or fee inputs are wrong.
Market demand is separate
A calculator can show the price needed for margin. It cannot prove that buyers will accept that price.
Professional advice is separate
FeeProofed is for planning and comparison. It does not replace tax, legal, accounting, lending, or financial advice.
FAQ
Calculator methodology FAQ
What is the FeeProofed calculator methodology?
FeeProofed builds each calculator around one business decision, visible math, editable assumptions, and source notes where outside rates affect the result. The goal is to make the number easy to inspect before a seller uses it.
Are FeeProofed calculators financial advice?
No. FeeProofed calculators are planning tools, not tax, legal, accounting, lending, investment, or financial advice. Users should confirm account-specific rules and use a qualified professional for high-stakes decisions.
Where do calculator defaults come from?
Platform-sensitive defaults should be tied to source notes when a published rate drives the math. Business inputs such as labor, product cost, shipping, and margin are editable starting points because the right value depends on the seller.
What does a reviewed or verified date mean?
A reviewed or verified date means the page was checked against its own formula, structure, and sources on that date. It does not mean an outside platform kept the same policy after that review.
How should I use a calculator result safely?
Start by replacing defaults with your real costs and account-specific fees. Then confirm official source rules before changing a live price, ad budget, or marketplace listing.
Why does FeeProofed avoid duplicate calculators?
One strong page is better when the search intent and formula are the same. Duplicate calculators make maintenance harder and make it less clear which answer a seller should trust.