Age Calculator
Your exact age in years, months and days — plus totals and a birthday countdown. Runs privately in your browser.
Your files never leave your device.
How to use the age calculator
- Enter your date of birth (or anyone's — it works for any date).
- Optionally set the "as of" date — leave it empty for today, or set it to a past or future date to answer "how old was I when…" or "how old will I be when…".
- Read the results: exact age in years, months and days; total days and weeks lived; and days until the next birthday.
Why "exact" age is harder than it looks
Years have 365 or 366 days; months have 28 to 31. Subtracting two dates by counting years × 365.25 gets you close but wrong by days at a time — and for things like retirement eligibility, exam cutoffs or visa rules, days matter. This calculator walks the real calendar: full years first, then full months (respecting their actual lengths), then the leftover days. A person born on 15 February 1990 checking on 3 March 2024 is exactly 34 years, 0 months and 17 days old — not "34.05 years".
The same careful counting powers the birthday countdown, including the February 29 edge case: leap-day birthdays get their celebration counted from February 28 in non-leap years.
Fun with milestone days
Age in years hides how much time has actually passed. Ten thousand days of life lands around age 27 years and 4 months; twenty thousand lands around 54 years and 9 months. Enter your birth date, look at the total days figure, and you can plan the celebration down to the day. The same trick works for work anniversaries, pets and relationships — "1,000 days together" is a better excuse for cake than most.
Common uses
- Forms and eligibility — "must be 18 on this date", retirement ages, exam age limits, insurance brackets.
- Milestones — your 10,000th day alive is a real thing people celebrate (it lands in your late twenties).
- Planning — how many days until the next birthday, anniversary or deadline date.
- Curiosity — total days and weeks lived put a life in a surprisingly concrete perspective.
Frequently asked questions
How is exact age calculated?
From your date of birth to today (or a chosen date), counting full years, then full months, then remaining days — taking into account the varying lengths of months and leap years. The totals (days, weeks) count whole elapsed days.
Can I calculate age as of a past or future date?
Yes. Set the Age at date field to any date — useful for checking eligibility dates, retirement ages or historical ages at a given event.
How does the calculator handle leap years?
By counting real calendar months and days rather than approximating with 365.25-day years. For the birthday countdown, February 29 birthdays are counted from February 28 in non-leap years.
What is my date of birth used for?
Nothing besides the on-screen calculation. It never leaves your browser — nothing is uploaded, logged or stored.