Age Calculator
Enter a date of birth to get an exact age in years, months and days, plus totals in months, weeks and days, and a countdown to the next birthday.
Everything you enter is processed in your browser and isn't sent to our servers.
How to use age calculator
- 1Enter a date of birth.
- 2Optionally change the "as of" date — it defaults to today.
- 3Read the exact age breakdown and total counts.
- 4Check the countdown to the next birthday.
About this tool
Calculating exact age sounds simple but is easy to get subtly wrong, especially around leap years and months of different lengths. This calculator uses full calendar-aware date arithmetic, so a birthday on February 29th or a target date at the end of a short month is handled correctly.
Alongside the years/months/days breakdown, the total months, weeks and days give a single-number view of age that's useful for things like eligibility rules, contest age limits, or just curiosity about a big round number of days lived.
The next birthday countdown finds the closest upcoming occurrence of the birth month and day relative to the chosen "as of" date, wrapping to next year if this year's birthday has already passed.
Frequently asked questions
The underlying JavaScript date engine treats a February 29th anniversary in a non-leap year as March 1st, which is the standard behavior most calendar tools use. Every other calculation — the years/months/days breakdown and totals — remains calendar-accurate.