Age Calculator — Exact Age from Date of Birth, Years Months Days

An age calculator answers a simple question: how old am I, exactly? Enter your date of birth and optionally an "age on date" — today or any past or future day — and this tool returns years, months, days, total days lived, weeks, hours, and days until your next birthday. Everything runs locally in your browser; your date of birth is never uploaded.

No app install or account is required. Pick two dates and read the breakdown instantly — useful for forms, eligibility checks, birthday planning, and genealogy research.

The most useful output is exact calendar age: for example, 36 years, 4 months, 14 days — not a rounded number. The calculator subtracts birth year, month, and day from the target date using borrow rules when days or months would otherwise go negative.

You also get:

• Years, months, and days in a single result line
• Total days between birth and the target date
• Total weeks and hours for milestones and trivia
• Countdown to your next birthday

Leap years and varying month lengths (28–31 days) are handled automatically — important for February 29 birthdays and month-end edge cases.

By default, the target date is today, giving your current age. Change the "Age on date" field to answer historical or forward-looking questions: how old was someone on their wedding day, a contract signing, or a historical event?

The calculator needs only two dates — birth and target. Examples:

• Set the target to a deadline to verify eligibility as of that day
• Enter the full date of birth, not just the birth year, for accurate month and day counts
• Leave the target at today for your present age

Future target dates show how old someone will be on that day — handy for planning milestones or verifying age requirements before an event.

Calendar age is not a single multiplication. It uses step-by-step date arithmetic:

1. Start with the year difference (target year − birth year)
2. Adjust months; if negative, borrow 12 months from the year count
3. Adjust days; if negative, borrow days from the previous month (whose length varies)

totalDays = floor((target − birth) ÷ 86,400,000 ms)

Enter dates in the picker and the calculator handles the borrow logic. Total days, weeks, and hours appear below the main years-months-days line for milestones and trivia.

Enter when someone was born and read their age back. Typical uses include:

• Forms asking for age in years and months (school admission, sports categories)
• Verifying eligibility as of a specific deadline
• Birthday planning — days until the next birthday
• Genealogy and family history — age of a relative on a historical date
• HR and ID checks — cross-checking stated age against date of birth

Because calculations run entirely in the browser, you can enter sensitive dates without sending them to a server.

Stay on-topic for accurate expectations. This tool does not provide:

• Gestational age, pregnancy weeks, LMP, or EDD estimates — medical obstetric tools use different clinical rules
• Biological age or health biomarker age — those use blood tests and statistical models, not date of birth alone
• Dating age-gap social rules — a separate concept from calendar age
• BMI or growth charts — those combine height and weight measurements, not dates alone
• Age estimation from photos — no image upload or AI analysis here
• Reverse calculation of birth date from age alone — you need at least a birth year; this tool goes birth date → age only
• Life expectancy projections

For calendar age from a known date of birth, you are in the right place.

Your dates never leave the device. Calculations use your browser's local timezone with midnight boundaries on the dates you pick.

Leap year (Feb 29): age is computed from the date you enter. In non-leap years some people observe Feb 28 or Mar 1 — pick the date you legally or personally use.

Calendar vs decimal age: legal age is usually whole calendar years (or Y-M-D). Some analytics use decimal years (totalDays ÷ 365.25); this tool shows calendar components plus total days for transparency.

Enter your date of birth, set the target date, and read exact age in years, months, and days below.