Age Calculator
Calculate exact age in years, months, days, weeks, hours, and minutes. Also shows days until your next birthday.
How to use this calculator
Enter your date of birth. The "as of" field defaults to today, but you can change it to calculate your age at any past or future date. The calculator breaks your age down into years, months, and days, plus totals in weeks, days, hours, and minutes — with the next birthday countdown at the bottom.
Why this isn't just subtraction
Calendar math is surprisingly tricky. Months have 28-31 days, leap years insert an extra day, and "X years, Y months, Z days" is ambiguous without a proper calendar walk. This calculator uses date-fns' calendar-aware algorithms, which handle edge cases (like someone born on February 29 turning "21 years old" on March 1 in non-leap years) consistently.
Useful angles for this calculator
Checking age-based eligibility cutoffs (driving, voting, drinking, retirement accounts), figuring out how old someone was in an old photo, calculating age at a specific past event, or just seeing where you stand against life-expectancy benchmarks. It's also a staple for genealogy and record-keeping.
Birthdays and time perception
A quirk of aging: each year is a smaller percentage of your life than the previous one, which is partly why later years feel "faster." A child's 10th birthday represents ~10% of their life; an adult's 50th birthday is just 2%. The math behind how old you are is simple. What it feels like — that's the complicated part.
Frequently asked questions
How does the calculator handle leap years?▾
It uses calendar dates rather than fixed 365-day years, so February 29 birthdays and leap-year overlap are calculated correctly. The totalDays figure counts actual days elapsed, not 365 × years.
Can I calculate someone's age on a future or past date?▾
Yes — change the 'as of' date. Useful for figuring out someone's age at a specific event (a wedding, a graduation, a historical date), or projecting your own age on a future date.
Why is my age in months different from my age in years × 12?▾
Because months have varying lengths (28-31 days). Total months is a true count of complete calendar months, not an approximation. For example, 5.5 years is 66 months even though 5.5 × 12 = 66 exactly — coincidentally right, but the calculator uses real calendar math either way.
What's the point of showing total minutes or hours?▾
Mostly curiosity — but the precision can matter for official documents (some legal age calculations count to the hour), or for people who want to mark specific milestones (a billionth second of life, for instance).
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