Date of birth, Age on
Waiting for input
How this calculator works
Age is counted the way most countries do it legally: you turn a year older on each birthday. The calculator shows completed years, months and days, the total number of days lived and how long until the next birthday. People born on February 29 are treated as having their birthday on February 28 in non-leap years.
Formula
- Age = date of calculation − date of birth, counted in whole calendar years, months and days
- Total days = date of calculation − date of birth
Worked example
Born May 15, 1990, as of October 7, 2026
- Date of birth
- 1990-05-15
- Age on
- 2026-10-07
Result36 years old
36 years, 4 months, 22 days as of Wednesday, October 7, 2026.
Frequently asked questions
How is age calculated exactly?
Count the completed years since the birth date, then the completed months since the last birthday, then the remaining days.
When does someone born on February 29 have a birthday?
In non-leap years this calculator uses February 28. Legal rules differ: some jurisdictions use March 1.
Can I calculate age on a past or future date?
Yes. Change the 'Age on' date to any date on or after the date of birth.
More date & time calculators
Results are estimates based on the values you enter and the published method shown above. They do not replace professional medical, financial or legal advice. Method reviewed October 7, 2026. About this site