Math Tools
Number Base Converter
Convert between binary, octal, decimal and hex, including very large numbers.
Math Tools
Age Calculator
Get your exact age, total days lived and the days until your next birthday.
Tool Panel
About Age Calculator
Age is computed as a calendar difference — years first, then borrowing a month or the previous month length when days or months go negative — which is not the same as dividing total days by an average month. Totals in days, weeks and months plus the next birthday are shown too.
- 1
Age is a calendar difference: subtract years first, then borrow the actual length of the previous month (28–31 days) when days or months go negative. That makes "X years Y months Z days" different from total days divided by an average month.
- 2
Totals in days, weeks (rounded down), months and the days until the next birthday are shown together so the different measures can be compared.
- 3
The next birthday is based on whether this year's date has passed, rolling to next year if it has; a 29 February birthday becomes 1 March in non-leap years, because Date normalises it.
- 1
Pick the birth date
Use the date control or type it in.
- 2
Read the age
The headline is "X years Y months Z days"; totals sit underneath.
- 3
Check the next birthday
It reads zero days when today is the birthday.
Because months vary in length. The calendar difference borrows the real length of the previous month, while "total days ÷ 30" treats every month as 30 days — an estimate that should not match. Both are given so you can use whichever your context needs.
JavaScript Date normalises 29 February to 1 March when the year has no leap day, so the next-birthday count follows that. It is the runtime's date rule, not an extra branch in this tool.
Related tools
View allMath Tools
BMI Calculator
Work out your body mass index and what the range means.
Math Tools
Math Tools
Mortgage Calculator
Work out monthly repayments and total interest on a loan.
Math Tools
Math Tools
Percentage Calculator
Work out percentages, ratios and growth rates.
Math Tools
Math Tools
Tip Calculator
Work out the tip, the total and each share from a bill amount.
Math Tools
Math Tools
Discount Calculator
Turn an original price and a discount percentage into the final price.
Math Tools
Math Tools
Scientific Calculator
An expression calculator with trigonometry, logarithms, powers and factorials.
Math Tools
Math Tools
Currency Converter
Convert amounts across 16 currencies using fixed reference rates.
Math Tools