Age Calculator

What this tool does

Calculate age from a date of birth to today or to any selected date. The calculator shows completed years, months and days, total months, weeks, days and hours, the weekday you were born, and the number of days until the next birthday.

Age is calculated with calendar dates rather than a simple average number of days per year, so month lengths and leap years are handled correctly. The tool runs entirely in your browser and does not send dates to ToolsDiary. For legal, insurance or eligibility decisions, use the rules required by the relevant authority because official age rules can vary by jurisdiction.

Useful for

• Check your exact age in years, months and days.
• Calculate age on a past or future reference date.
• Find total completed months, weeks and days lived.
• See the weekday of birth and the next birthday countdown.

How to use it

1. Choose the date of birth.
2. Leave the “Calculate age on” field set to today, or choose another date.
3. Select Calculate age to see the exact calendar age and totals.
4. Use Reset when you want to start a new calculation.

Practical tips

• Use the actual date of birth shown on the relevant record when accuracy matters.
• The “total months” figure counts completed calendar months, while total days is based on the exact date difference.
• For a February 29 birthday, the next-birthday countdown uses February 28 in non-leap years.
• Dates stay in your browser; the calculator does not upload or store them on ToolsDiary.

Frequently asked questions