How age is calculated
Count the full years since the birth date, then the full months since the last birthday, then the remaining days. Someone born on February 29 is usually treated as turning a year older on February 28 or March 1 in non-leap years, depending on the rule being used.
Ages that matter in the US
| Age | What it usually means |
|---|---|
| 16 | Driver's license in most states |
| 18 | Legal adult: vote, sign contracts, serve on a jury |
| 21 | Legal drinking age nationwide |
| 26 | Coverage on a parent's health plan usually ends |
| 50 | Extra catch-up contributions to 401(k)s and IRAs |
| 59½ | Withdraw from retirement accounts without the 10% penalty |
| 62 | Earliest age to claim Social Security |
| 65 | Medicare eligibility |
| 67 | Full Social Security retirement age if born in 1960 or later |
Why months and days are tricky
Months have different lengths, so "1 month" after January 31 isn't a fixed number of days. This calculator counts whole months from your birth date, then the remaining days, the same way you'd count on a calendar.
Frequently asked questions
Can I find my age on a past or future date?
Yes. Change the second date to any day to see how old someone was or will be on that date.
Why do some countries count age differently?
A few cultures traditionally counted a newborn as one year old. Most countries, including the United States, use the international method shown here.