How every number on this site is computed

A site that publishes numbers about money owes its readers an account of where they came from. This is that account, and it is deliberately short enough to check.

The engine is the only source of our own figures

Every euro figure on this site that describes a store, from the worked example inside a calculator to the fourteen-month anatomy in a data study, is computed by the same code that computes a paying customer’s profit and loss statement. Nothing is typed in by hand, and nothing is rounded into a nicer shape for a headline.

That matters most where a page shows two numbers at once. A waterfall beside a screenshot, a table beside a calculator default, a study beside a glossary definition: all of them read from one run of one engine, so they cannot drift apart while somebody edits a paragraph.

The example store, and why it is not customer data

Our worked examples come from a generated store: a realistic catalogue, fourteen months of orders, refunds, discounts, several payment gateways, shipping zones with weight brackets, packaging fees and a fixed cost book. It is priced by the real engine under the real recognition rules, and it is not any merchant’s business.

We use it because the alternatives are worse. Real customer data cannot be published, and invented benchmarks presented as industry figures are the thing this category does far too much of. A generated store is honest about being one, and every page that uses it says so.

The recognition rules behind every figure

Sales and their cost of goods belong to the order date. Refunds belong to the day the refund was issued, never backdated against the order they reverse. Advertising belongs to the day it was spent, taken from each platform’s billing side rather than from attributed revenue. Recurring fixed costs are spread across the days they cover, and one-off costs land on the day they were booked. Every date is in the store’s own timezone.

Costs carry the day they took effect, so an order is priced by the rule that was true on its own date, and a later cost change never rewrites a closed day. Cancelled and test orders are excluded everywhere. VAT is removed from what was kept rather than from what was sold, so a refund hands its tax back too.

Competitor prices, and how they are dated

Every competitor price on this site was read from that vendor’s own published page and carries the date it was checked, in the prose rather than in a footnote. When we write or revise a comparison we re-read the pricing pages that day rather than trusting an earlier note, because prices in this category move within weeks.

Our own prices are never typed into an article at all. They are interpolated from the same plan data the checkout charges from, so a page cannot quote a price the product does not sell.

What we refuse to publish

• Ratings, review scores or star counts for ourselves or anybody else, including in structured data where only a crawler would see them.
• Customer testimonials until real ones exist, which is why the landing page currently has none.
• Industry benchmarks we did not measure, and survey figures we did not run.
• Maintained rate tables for packaging schemes or payment gateways, because those are quoted privately and revised annually; every calculator takes the merchant’s own rate as an input instead.
• Compliance advice. We compute what a regulation costs, never who must register or what is owed.

What the calculators share with the product

The public calculators are not a separate implementation. Each one runs the same arithmetic the statement uses, and a test feeds a real engine statement back through every calculator and requires it to reproduce the engine to the cent, including on a split payment. A public tool that disagreed with the product by a cent would undo the one thing the product sells.

Every result row carries the statement line number it corresponds to, so a figure in a calculator can be traced to the line it would occupy on a real profit and loss statement.

When something here is wrong

Two things have already been corrected rather than quietly adjusted: a claim about how Shopify handles historical unit costs, and a rounding rule that lost a fraction of a cent on every parcel. Both are described in the posts they affect. If you find another, tell us and it will be fixed with the correction visible rather than the page silently rewritten.