About CalcOtter

Methodology

Every calculator on CalcOtter is a small, transparent program: the formula it uses is printed on its own page with a worked example, and the code behind it is automatically tested against published reference values before any change goes live — standard amortization tables for the loan math, WHO classification bands for BMI, the Mifflin–St Jeor equation for calories, and the exact international definitions for unit conversions (1 inch = 25.4 mm, 1 lb = 0.45359237 kg). If a number here ever disagrees with a textbook, the textbook wins and we fix it.

Privacy by architecture

Calculations run entirely in your browser. Loan amounts, body measurements, and dates are never transmitted to a server, because there is no server doing the math — the pages are static files. Once a page has loaded, it works with the connection off.

What the numbers are — and aren't

These are calculators, not advisors. Financial results are projections at the rates you enter, ignoring tax, fees, and rate changes; health numbers are population-level screening formulas, not diagnoses. For decisions that matter, take the number to a professional — it will make the conversation faster.

How the site sustains itself

CalcOtter is free and supported by a single advertisement per page, clearly labelled, in a fixed spot that never shifts the layout or hides the answer. No accounts, no paywalled features, no selling of data — there is no data to sell.