How these calculators work

Everything runs in your browser

There is no server doing the maths. Each page loads a small calculator definition and a shared engine; your inputs never leave the tab. That also means the tools work offline once loaded.

Formulas are stated

Every calculator names the formula it uses — Heron's for triangles, Mifflin-St Jeor for calories, the US Navy method for body fat, reducing-balance amortisation for loans. If a result looks wrong, you can check the arithmetic rather than trusting a black box.

Assumptions and limits

Each result carries a note listing what is excluded — tax, fees, provincial levies, individual variation. These are planning tools, not quotes, medical advice or tax filings.

Accuracy

Inputs are validated (a triangle that cannot close returns an explanation, not a number). Where a rate is a market or statutory figure, the year is stated on the page.