Every calculator on this site is built from a preset: one firm program, its rules as the firm publishes them, the date we last checked, and the sources. This page explains the standard, because the standard is the product.
A preset ships only after we have read the rule on the firm's own website or help centre. Third-party comparison sites, videos and forum posts are never a source, however recent. When a firm's own pages disagree with each other (it happens — The5ers currently states different daily limits on two pages), we encode the tighter value, show an amber banner naming the conflict, and ask the firm directly; the transcript is kept.
Most rule differences hide in five words: balance or equity; initial or day-start; higher of; trailing; locks. Each preset records which apply, and the calculator page prints the definition beside the input so you can check it against your own dashboard.
Presets are re-checked against the firms' pages every week. When a rule changes, the preset changes as a new dated version, never an edit, so anyone can see what the rule was on any given day.
The arithmetic runs through an engine verified against 198 rule vectors written by an independent implementation, and the two are audited against each other continuously. When either finds a defect, both are fixed and the finding is recorded. Nothing you see here is a number one person typed once.
Guess. Where the tool cannot resolve a currency conversion, a contract size or a rule, it says so and refuses to size the trade. A wrong number with confidence is worse than no number.
Bulwark shows rule mathematics — general information, not financial advice. Always verify against your firm's dashboard.