Disclaimer
Every tool here produces an estimate. Here is what that means in practice.
General
All results on this site are estimates provided for general information and educational purposes. They are not professional advice and are not tailored to your circumstances.
Health tools
The BMI, body fat, calorie, ideal weight, heart rate, pregnancy and related calculators use general population formulas. They cannot account for your medical history, body composition, medication, or anything else that makes you an individual.
They are not a diagnosis and must not be used to make medical decisions. BMI in particular is a crude screening measure with well-documented limitations, described on the BMI calculator page itself. If a result concerns you, speak to a doctor.
Financial tools
Loan, mortgage, interest, tax, salary and retirement calculators use standard formulas and the figures you enter. Real financial products carry fees, conditions, rate changes and tax treatments that a simple calculator cannot capture.
Your lender's or tax authority's figures are the ones that count. Tax tools in particular are simplified estimates and vary enormously by jurisdiction and personal situation.
Date, time and conversion tools
These are arithmetically precise, but conventions differ. Whether a date range includes both end days, whether "a month" means a calendar month or 30 days, and whether a gallon is US or imperial all change the answer. Each page states the convention it uses — check it matches the one your situation requires.
Random and decision tools
Coin flips, dice, name pickers and wheel spinners use your browser's random number generator. They are suitable for games, giveaways and choosing where to eat. They are not certified for gambling, legal lotteries, or any purpose requiring audited randomness.
Reporting an error
If a tool gives a result you believe is wrong, please get in touch and say which tool and what inputs you used. Corrections are published promptly.