Age Calculator — Exact Age in Years, Months and Days
Calculate your exact age in years, months and days, plus total weeks, days and hours, the day of the week you were born and a countdown to your next birthday.
How to use the age calculator
Enter a date of birth. The age appears immediately, measured to today in your own time zone. To find an age on another date, change the second field — useful for eligibility cut-offs, insurance forms or working out how old someone was when something happened.
What the numbers mean
- Age — whole years, then the months and days since the last birthday, which is the form used on official documents.
- Months, weeks and days — the same span counted in a single unit. Weeks are whole weeks only.
- Hours — days multiplied by 24. It ignores the time of day you were born, so treat it as an approximation.
- Next birthday — how many days away it is, the date, and the age you will turn.
Why age calculations are trickier than they look
Dividing the number of days by 365 goes wrong around leap years, and dividing by 365.25 goes wrong right around birthdays — both can be a day out exactly when it matters most. This calculator works in calendar units instead: it counts whole months, then days, the way a person would with a calendar in front of them.
All the arithmetic is done on dates alone, with no clock times involved, so a daylight-saving change between the two dates can't shift the result by a day.
Ages that often matter
- School entry — most school systems use a cut-off date, so the age on that exact date decides which year a child joins.
- Legal majority — 18 in most of Europe and the Americas, which affects contracts, voting and driving.
- Pensions — state pension ages are rising in many countries and are often set to the month, not just the year.
- Insurance and loans — premiums and eligibility frequently change on a birthday, so the days until the next one can matter.
Frequently asked questions
How is the exact age calculated?
First the calculator counts the whole months between the two dates, then turns every twelve of them into a year, then counts the days left over. That's how people naturally state an age — “34 years, 2 months and 5 days” — rather than dividing a day count by 365.25, which drifts by a day or two.
What if someone was born on 29 February?
In years without a 29 February, the calculator treats 28 February as the birthday, which is the most common convention. Some countries use 1 March for legal purposes such as the age of majority, so check local rules if the exact day matters legally.
Why does a month count differently at the end of a month?
Months have different lengths, so “one month after 31 January” has no exact answer. The calculator follows the usual rule of moving to the last day of a shorter month: one month after 31 January is 28 February (or 29 in a leap year).
Can I find someone's age on a past or future date?
Yes. Change the “Age on” date to any day — for example, to check how old someone was on a historical date, or whether a child will have reached a school's cut-off age by 1 September.
Related tools
Percentage Calculator
Five percentage modes, from tips and discounts to percent change.
Open toolDays Between Dates
Count calendar days and Monday–Friday business days between dates.
Open toolQR Code Generator
Make QR codes for links, Wi-Fi and text. PNG or SVG, never expires.
Open toolLast updated September 25, 2026