Calculators
Percentages, dates and the everyday arithmetic that is easy to get subtly wrong.
Each calculator states the formula it applies, so you can check the result rather than trust it. Where a calculation depends on a rule that varies by country, the rule and its source are shown with the answer.
How old someone is in years, months and days, and how long until the next birthday.
Compound Interest CalculatorWhat a balance grows to over time, with or without regular contributions, and how much of it is interest.
Date Difference CalculatorHow long between two dates: the exact number of days, and the same gap in weeks, months and years.
Discount CalculatorThe price after a discount, what you save, and what a second discount on top actually comes to.
Inflation CalculatorWhat an amount in one year is worth in another, from the World Bank consumer price index, for the countries and years it actually covers.
Loan CalculatorWork out the payment on a loan, what it costs in total, and how the balance falls year by year.
Percentage CalculatorWork out a percentage of a value, a ratio as a percentage, or an increase, a decrease and a percentage change.
Tip CalculatorWork out a tip, the total, and what each person owes when the bill is split.
Unit Price CalculatorCompare packs by their price per kilo, per litre or per piece, and see which is really cheapest and by how much.
VAT CalculatorAdd VAT to a net amount or take it back out of a gross one, at any rate you type — with a few official rates ready to pick.
Working Days CalculatorCount the working days between two dates, on the working week you actually use.