About the Age Calculator
This calculator gives an exact age from a date of birth: years, months and days, calculated with awareness of different month lengths and leap years. It also shows the total days lived, the day of the week the person was born on, and a countdown to the next birthday. Enter the birth date in the pane, and optionally a different reference date in the toolbar to find age as of that day.
The awkward case is a birthday on 29 February. Three years in four that date does not exist, so this calculator treats 28 February as the day the age ticks over, which matches how most forms and legal systems behave, though a few jurisdictions use 1 March instead. Check the local rule if the answer has to stand up officially. The total days figure counts every leap day that has actually passed, which is why it usually comes out a few days above years multiplied by 365.
Beyond curiosity it answers eligibility questions precisely: whether someone had turned 18 on the day a contract was signed, or how old a patient was when a recorded event took place. Set the reference date in the toolbar to any past or future day to get an age as of that moment rather than today. Dates can be in almost any format. For the gap between two arbitrary dates rather than an age, use the Date Difference Calculator; to shift a date by a fixed period, Add or Subtract Time.
How to use
- Enter the date of birth in the pane.
- Optionally set a reference date other than today.
- Read the age and next birthday.
Common questions
- Are leap years handled?
- Yes, the calculation is calendar-aware, so someone born on 29 February is handled correctly.
- Can I find age at a past or future date?
- Yes, set the "On date" in the toolbar to any date.
- What if the birth date is in the future?
- It is reported as an error, since age would be negative.