Free calculator widgets for your website

Calculate your monthly mortgage payment, total interest paid and loan amount using standard amortization. Includes the 28/36 affordability rule.

Calculate your Body Mass Index instantly with WHO classification and NHS ethnicity-adjusted thresholds. Metric & imperial, healthy weight range included.

Calculate the monthly payment, total paid, and total interest for any amortizing loan. Enter amount, annual rate, and term in months.

Calculate your exact age in years, months and days from your date of birth, plus total days, weeks, months lived and days until your next birthday.

Calculate percentages three ways: find a percent of a number, find what percent one number is of another, or calculate percent change between two values.

Calculate compound interest with A = P(1+r/n)^nt. Choose annual, quarterly, monthly or daily compounding. Includes Rule of 72 doubling-time estimate.

Calculate daily calories to maintain, lose or gain weight using the Mifflin-St Jeor equation, activity multipliers and safe minimum-calorie floors.

Calculate your GPA on the 4.0 scale with credit weighting: quality points, total credits and a letter-grade conversion table for the common US convention.

Estimate your retirement nest egg using compound growth and the Bengen 4% safe-withdrawal rule. See projected monthly income in today's dollars.

Estimate your pregnancy due date from your last menstrual period, conception date, or IVF transfer using ACOG Naegele's Rule and ASRM conventions. Free tool.

Estimate income tax using US 2025 federal brackets or UK 2025-26 bands. See tax due, after-tax income, and effective rate. Educational reference only.

Calculate your Total Daily Energy Expenditure with the Mifflin-St Jeor equation and standard activity multipliers. Maintenance, loss and gain estimates.