Disclaimer
Every calculator here has limits. This page states them plainly, category by category.
General
All results are estimates produced by a formula applied to the numbers you entered. A calculator has no knowledge of your circumstances and cannot tell you when its assumptions do not fit your case.
Health and fitness
BMI, body fat, calorie and BMR calculators use general-population formulas. They do not account for muscle mass, athletic build, pregnancy, medical conditions, medication or age extremes. BMI in particular misclassifies muscular people as overweight. Do not use these figures to justify a restrictive diet without speaking to a doctor or dietitian.
Children's growth
The children's BMI calculator converts BMI to an age-and-sex percentile using a growth reference. Percentiles near the overweight and obese cut-offs are sensitive to small differences in that reference data. Any concern about a child's growth belongs with a paediatrician, not a website.
Pregnancy and fertility
Due dates, ovulation windows and conception dates are estimates based on an average cycle. Real cycles vary from person to person and month to month. An ultrasound dating scan is more accurate than any calculation. These tools are not contraception and must not be relied on to avoid pregnancy.
Finance
Loan and mortgage figures assume a fixed rate and a regular schedule. They exclude fees, insurance requirements, early-repayment charges, rate changes and tax treatment specific to your country. Your lender's own quote is the number that counts. Nothing here is investment advice.
Zakat and Islamic finance
The zakat calculators apply widely cited weights and rates, and ask you to supply the current gold or silver price yourself so the result is accurate on the day you use it. They cannot verify that you have held wealth for a full lunar year, nor account for every school's position on every asset. Where the Hanafi and Shafi'i positions differ, both are shown. These tools are a calculation aid and not a religious ruling — confirm anything consequential with a qualified scholar.
Academic grades
Grade, GPA and CGPA conversion formulas differ between institutions, and the widely used multipliers are conventions rather than universal rules. Each converter states the formula it applies. Before quoting a converted figure on an application or transcript, check it against your own institution's published rule.
Dates and calendars
Hijri dates use the tabular Islamic calendar, which is arithmetical and predictable. Locally observed dates depend on moon sighting and can differ by a day in either direction. For religious observances, follow your local authority.
Reporting an error
If a calculator gives a result you believe is wrong, please tell us with the numbers you used. We would rather fix it than defend it.
This page was last reviewed on 11 August 2026.