Age Calculator
Pick your date of birth for a complete life dashboard: calendar age, totals (days/weeks/hours/minutes/seconds), born weekday, next birthday countdown with weekday, dog/cat years, retirement countdown and percentage of average life expectancy.
Calculations happen in your browser. No data is sent to a server.
How to use this age calculator
- Pick your date of birth (and optionally a different 'as of' reference date).
- See your calendar age and total time alive in days, weeks, hours, minutes, seconds.
- Check your born weekday and the countdown to your next birthday with its weekday.
- Set a retirement age to see the countdown and target retirement date.
Frequently asked questions
How are dog years calculated?
Modern dog-year formula: 15 for the first year, +9 for the second, then +5 per year. Cat years use +4 per year after age 2.
What does 'as of' mean?
By default it's today. Change it to calculate someone's age at a specific past or future date — useful for paperwork or planning.
Does it account for leap years?
Yes. Calendar math is exact and respects leap years and varying month lengths.
Why does the calendar age sometimes show one day less than I expect?
Age in years/months/days only counts complete units. If you were born on Feb 29, your birthday on non-leap years is treated as Mar 1 by default — meaning your 'birthday' day-of-week shifts by one. Set the 'as of' date to Feb 28 to see the alternative count.