Age Calculator
Enter your date of birth to find your exact age in years, months, days, and hours. See your next birthday countdown.
Quick Ages — How old would they be today?
How to use Age Calculator
The age calculator computes the exact age between any two dates — date of birth and a target date (default: today) — in years, months and days. It also shows total days lived, approximate total hours, the day of the week you were born and how many days until your next birthday. The precise breakdown is useful for legal documents, medical records, milestone tracking and general curiosity.
- Enter your date of birth.
- The target date defaults to today — change it to calculate age at any historical or future date.
- Read your age in years, months and days, plus total days and hours.
- Check the day of birth and days until next birthday.
Your data never leaves your device — 100% private processing.
How age is calculated precisely
Age in years is the number of complete Gregorian calendar years elapsed. Months count completed months after the last birthday year. Days count the remaining days after whole months. This calendar arithmetic means someone born on February 29 (leap day) has a birthday only on actual February 29 in leap years — other years the birthday is counted on February 28 or March 1 depending on jurisdiction.
Age for legal and medical purposes
Legal age thresholds (18, 21, 65) are triggered on the exact birthday, not the day before or after. Medical age is often expressed in total months for young children (24 months rather than 2 years) because developmental milestones are more granular. The tool provides all formats so you can use the representation appropriate for your context.
| Age | Milestone | Notes |
|---|---|---|
| 13 | COPPA protection ends | Children under 13 have extra online privacy rights |
| 16 | Driving (most US states) | Learner permit; full licence typically at 17–18 |
| 18 | Age of majority | Legal adult: vote, sign contracts, join military |
| 21 | Alcohol (US) | Legal drinking age in the United States |
| 62 | Early Social Security | Earliest US Social Security benefit claim age |
| 65 | Medicare eligible | US federal health insurance eligibility |
Glossary
- Gregorian calendar
- The internationally accepted civil calendar, with 365 days per year and a 366-day leap year every 4 years.
- Leap day
- February 29, which occurs only in leap years.
- Age of majority
- The legal age at which a person is considered an adult, typically 18 in most countries.
- Gestational age
- Age measured in weeks from the start of the last menstrual period, used for newborns and infants.
Related reading
Frequently Asked Questions
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Why use Age Calculator?
- Step-by-step explanations alongside every calculation
- Printable or shareable result summaries
- Works entirely offline in your browser
- Built-in input validation prevents common mistakes
Common use cases
- Calculate loan repayments before applying
- Check compound interest on savings accounts
- Estimate tax owed before filing
- Work out break-even point for a new business
- Plan retirement savings contributions
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