Age Calculator
Calculate your exact age, the difference between two dates, or add and subtract time from a date — all in one tool, calculated instantly in your browser.
Enter a date of birth to calculate age.
Enter both dates to calculate the difference.
Enter a start date to calculate.
| Mode | Use it for |
|---|---|
| Age Calculator | Exact age in years, months and days, plus days until your next birthday |
| Date Difference | How many years, months, days or weeks between any two dates |
| Add / Subtract Days | Find a date a certain number of days, weeks, months or years away |
Every date you enter is calculated locally in your browser using JavaScript. Nothing is sent to a server, stored, or shared — this includes your date of birth.
How this calculator works
Month and year additions clamp to the last valid day: January 31 plus one month becomes February 28, or 29 in a leap year. This calculator treats a February 29 birthday as February 28 in other years. Legal age rules can use a different convention. Zodiac and generation details are for fun; the Chinese zodiac uses the calendar year rather than the exact Lunar New Year.
All three modes use calendar-correct date arithmetic — not a rough estimate based on treating every year as exactly 365 days. Age and date differences are calculated by comparing year, month and day components directly, so leap years and different month lengths are handled correctly.
Everything runs in your browser using JavaScript's built-in date handling. There's no server involved, so results appear instantly and nothing you enter — including your date of birth — is ever transmitted anywhere.
Common uses
| Situation | Use this for |
|---|---|
| "How old am I exactly?" | Age Calculator |
| Checking age eligibility on a future date | Age Calculator, with "age as of" set ahead |
| Counting days until an event or deadline | Date Difference |
| Planning a due date, anniversary, or renewal | Add / Subtract Days |
| Figuring out a date 90 days before/after another | Add / Subtract Days |
Frequently asked questions
How accurate is this age calculator?
It calculates your exact age using calendar-correct year, month and day arithmetic — not a rough estimate based on 365-day years — so results are accurate down to the day, including for leap years.
Does this tool store or send my birth date anywhere?
No. Every calculation runs locally in your browser using JavaScript. Nothing you enter is sent to a server or saved.
Can I calculate age as of a date other than today?
Yes. The "age as of" field defaults to today but can be set to any past or future date, which is useful for eligibility checks or planning ahead.
Can I find the number of days between two dates?
Yes, the Date Difference tab calculates the exact difference between any two dates in years, months and days, plus the total number of days and weeks.
Can I add or subtract time from a date?
Yes, the Add or Subtract tab lets you add or subtract a number of days, weeks, months or years from any date and see the resulting date and day of the week.
Is this age calculator free?
Yes, completely free with no account or signup required.
Examples and practical checks
Understand the result before using it elsewhere.
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