Age Calculator

An age calculator gives the exact difference between two dates, broken down into years, months, and days. This is useful for official documents, medical records, insurance forms, or just satisfying curiosity about exactly how old you are today.

• Official forms: Quickly verify or confirm exact age in years/months/days for documents.
• Medical history: Doctors often need patient age in exact terms for age-sensitive treatments.
• Milestone birthdays: Find out exactly how many days until a 30th, 50th, or 100th birthday.
• Historical research: Calculate how old a historical figure was at a particular event.

1. 1Enter your date of birth in YYYY-MM-DD format.
2. 2Enter the target date (leave as today's date or change to a specific date).
3. 3The calculator subtracts the birth date from the target date using proper calendar arithmetic.
4. 4Month lengths and leap years are handled correctly.
5. 5Results show years/months/days plus total days, weeks, and months.

• Entering the date in the wrong format: The calculator expects YYYY-MM-DD format. Entering "03/15/1990" instead of "1990-03-15" may produce an error or wrong result depending on how your browser interprets the date picker.
• Using birth year instead of birth date: Age in years is straightforward from the year. But exact age in months and days requires the full date including month and day. A year-only entry will not give an accurate days-until-birthday count.
• Confusing age calculation with date difference: Age calculation steps down from years to months to days, adjusting for month length. Simple date subtraction in days gives a different breakdown. This calculator uses the birthday-stepping method to match how humans count age.
• Expecting age to match across time zones: Age changes at midnight local time. If you are comparing ages across time zones, the date picker uses your local date, which may differ from the birth location's date.

• Use it for contract and eligibility checks: Age thresholds in contracts (18 for adults, 65 for retirement benefits, 62 for early withdrawal) require exact dates. The calculator gives the precise age on any target date, not just today.
• Check age at a future date: Change the reference date to a future date to find how old someone will be on a specific occasion: at a wedding, at the start of school, or at a contract expiration. The calculator works for any reference date.
• Track days until next birthday: The days-until-birthday result counts down to the next occurrence, not just the next calendar date. This accounts for whether the birthday has already passed in the current year.
• Use for medical age documentation: Medical forms sometimes need age in months (e.g., for pediatric dosing). The calculator gives exact age in months alongside years and days, which is more precise than rounding to the nearest year.