We publish our process in full because trust should be inspectable, not assumed. Here's exactly what happens before a calculator reaches you — the same six steps we try to follow for every tool.
A calculator that's wrong is worse than no calculator at all — it gives you false confidence. So we treat every tool like a small piece of engineering: sourced, tested, documented, and dated.
We aim to take each calculator through all of these before it's published. If a step can't be done honestly, we hold the tool back.
We start with the authoritative source — a government agency, a recognised engineering standard, or peer-reviewed work. Never a half-remembered formula or a number copied from another calculator site.
Why it matters: the entire result rests on this. A wrong starting formula can't be fixed by good design.
Before anything is built, we check the formula against known reference values and edge cases. If a textbook says a given input should produce a given output, we check ours against it.
Why it matters: this is where transcription errors and unit mix-ups get caught — long before you ever see the tool.
The tool itself is plain, fast, and works on a phone. We test boundary inputs — zero, negatives, extremes — so it shouldn't show nonsense or fail silently.
Why it matters: a calculator should degrade gracefully, telling you when an input is out of range instead of returning a confident wrong answer.
Every calculator includes a real scenario with real numbers, walked through step by step. You can follow the arithmetic yourself and confirm the tool agrees.
Why it matters: a worked example turns a black box into something you can actually understand and trust.
Every formula links back to its source. We also name the assumptions and limitations openly — what the calculator accounts for, and just as importantly, what it doesn't.
Why it matters: honest limits are a feature. You should know the boundaries of a number before you rely on it.
A calculator isn't finished when it's published. We revisit tools over time and keep them current as sources and standards change.
Why it matters: accountability. A tool we keep current is one you can keep relying on.
Formulas get revised. Standards change. Agencies update their guidance. A tool that was correct two years ago can quietly drift out of date — and most calculator sites never notice.
We treat publication as the beginning, not the end. When a source changes, we update the affected calculators so they keep reflecting the current standard.
When we learn an agency has revised a formula or a standard, we aim to update the affected calculators and re-date them.
Holding every tool to these six steps means we simply can't publish hundreds at once — and that's the point. We'd rather publish fewer tools we've looked at carefully than many we haven't. The library grows steadily, one considered addition at a time.
Real requests shape what we build next — one carefully made, fully sourced tool at a time.
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