Free Online Calculators
Calculate age, BMI, mortgage payments, loans, interest, percentages, discounts, VAT, tips, dates, working days, currency and U.S. debt.
US Debt Calculator
See live U.S. national debt, GDP and the debt-to-GDP ratio using official Treasury and World Bank data.
Scientific Calculator
A calculator with square roots, sine, cosine, tangent, squares and percentages, in addition to the standard four operations.
Family Budget Calculator
Calculate your monthly family budget, track household expenses, and see how much money you have left for savings and other goals.
Age Calculator
Enter your date of birth to find your exact age in years, months and days, with leap years handled automatically.
BMI Calculator
Enter height and weight to calculate BMI and view the standard adult category. BMI is a general screening estimate, not a diagnosis.
Mortgage Calculator
Estimate the monthly principal-and-interest payment from the home price, down payment, interest rate and loan term.
Loan Calculator
Estimate monthly payments, total repayment and total interest from the loan amount, rate and term.
Compound Interest Calculator
See how an initial deposit and regular contributions may grow over time with compound interest.
VAT Calculator
Enter a price and VAT rate to calculate the tax amount, gross price or net price instantly.
Percentage Calculator
Calculate a percentage of a number, percentage increase or decrease, and the percentage difference between values.
Discount Calculator
Enter the original price and discount percentage to calculate the final sale price and how much you save.
Currency Converter
Convert amounts between major currencies using the latest available reference exchange rates.
Date Difference Calculator
Choose two dates to calculate the exact number of days between them quickly and accurately.
Working Days Calculator
Choose a start and end date to count weekdays and business days in the selected period.
Tip Calculator
Calculate the tip, total bill and amount each person should pay when splitting a restaurant bill.
13 everyday calculators — Age, BMI, Mortgage, Loan, Compound Interest, VAT, Percentage, Discount, Currency Converter, Date Difference, Working Days, Tip and U.S. Debt — all calculate live as you type, with no submit button and no data leaving your browser except for Currency Converter and U.S. Debt, which fetch live reference data from free public APIs (the European Central Bank via frankfurter.app, and the U.S. Treasury and World Bank respectively).
Mortgage and Loan use standard amortization formulas and are meant for quick estimates, not a substitute for figures from your actual lender — they don't account for fees, taxes or insurance. Working Days counts Monday through Friday only and doesn't exclude public holidays. The most-used calculators tend to be BMI, Tip and the Age Calculator for quick everyday math.
A few examples of what people use these for: comparing two job offers with different salaries using the Currency Converter, checking whether a 20% or 30% down payment changes a monthly mortgage payment enough to matter, splitting a restaurant bill fairly with the Tip Calculator, working out how many working days are left before a project deadline, or estimating how much a lump sum could grow over 10 years with the Compound Interest Calculator before deciding whether to invest it.
None of these need installing — they run directly in the browser on desktop, tablet or phone, and every result updates instantly with no submit button. Two things worth flagging before you rely on a number: BMI is a general screening estimate, not a medical diagnosis, and Mortgage and Loan estimate principal and interest only, so an actual lender's payment will also include fees, taxes and insurance the calculators don't account for.