Age Calculator
Free online age calculator. Calculate your exact age in years, months, days, and seconds from your date of birth instantly.
Defaults to today. Change to find an age on a future or past date.
Your age
25 yrs 0 mo 0 d
Life progress
31.2%
Total months
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Total weeks
—
Days lived
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Hours
—
Minutes
—
Next birthday
—
—
Zodiac
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Chinese: —
Method
How this calculator works
Age is the calendar difference between two dates. We compute years, months, and days separately so the result reads naturally — e.g. 25 years, 3 months, 14 days.
age = asOfDate − birthDate
years = asOf.year − birth.year
months = asOf.month − birth.month
days = asOf.day − birth.day
# borrow if day/month is negative
if days < 0: months -= 1; days += daysInPrevMonth
if months < 0: years -= 1; months += 12- Subtract the birth year from the current (or "as of") year.
- Subtract the birth month from the current month. If negative, borrow 1 from the years and add 12 months.
- Subtract the birth day from the current day. If negative, borrow days from the previous month.
- Convert the millisecond difference into total days, weeks, hours, and minutes for the secondary metrics.
- Determine zodiac sign from the birth month/day, and Chinese zodiac from the year mod 12.
Examples
Worked examples
Real numbers, end-to-end results.
Born June 12, 2004 · today June 5, 2026
21 years, 11 months, 24 days
8,028 days · zodiac Gemini
Born January 1, 2000 · today January 1, 2025
25 years, 0 months, 0 days
A nice round 25th birthday.
Born December 31, 1990 · today June 5, 2026
35 years, 5 months, 5 days
Capricorn · 12,940 days lived.
Use cases
When to use it
- Quickly tell someone exactly how old they are — to the day.
- Verify eligibility for age-restricted events, scholarships, or insurance products.
- Calculate the age of a child, pet, or historical figure on any specific date.
- Find how many days until a future birthday or anniversary.
- Plan retirement, school admission, or any milestone tied to date of birth.
FAQ
Frequently asked questions
How is my exact age calculated?
Does the calculator account for time zones?
Can I calculate my age on a specific future date?
Is a person born on Feb 29 a year older on Feb 28 or March 1 in non-leap years?
How are months calculated?
Methodology, assumptions & limitations
How we calculate: This calculator uses standard, peer-reviewed mathematical formulas implemented in TypeScript. All calculations run entirely in your browser — no data is sent to any server.
Assumptions: Unless stated otherwise, calculations assume constant rates over the specified period, no taxes or fees beyond those explicitly input, and standard compounding conventions for the formula type.
Limitations: Results are estimates for planning purposes. Real-world outcomes may differ due to variable rates, regulatory changes, taxes, fees, inflation, or other factors not modeled. This tool does not constitute professional advice.
When NOT to use this: Do not rely solely on this calculator for critical decisions where exact precision is required beyond the decimal places shown.
Feedback: Found an error or have a suggestion? Contact us — we review and correct reported issues within 48 hours.
Deep Dive Guide
How to Calculate the Age Difference Between Two People
Learn how age gap calculation works using calendar date subtraction. Understand years-months-days vs total days, and when age differences matter.
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