Age Calculator
Calculate exact age from birth date
100% free. Runs entirely in your browser - your files and data never leave your device and nothing is uploaded to any server.
All dates and times follow your device's time zone
About this tool
Age sounds like the simplest calculation there is, and it has more edge cases than almost any other date operation. The convention most of the world uses - your age increments on your birthday - is not universal: the traditional East Asian reckoning counts you as one at birth and adds a year at new year, which can put you two years ahead of your Western age. Even within one system, precision matters for different reasons. Forms want completed years. Medical records for infants want months. Legal thresholds - driving, voting, drinking, retirement - hinge on a specific date, not a rounded number, and being one day short is decisive. Then there is 29 February: someone born on a leap day has no birthday in three years out of four, and jurisdictions genuinely differ on whether they legally age on 28 February or 1 March. This gives an exact years, months and days figure with leap years handled correctly, calculated in your browser.
How to use this tool
- Enter the birth dateWatch the date format - 03/04 means March 4th in the US and 3rd April in most other places.
- Set the end date if neededDefaults to today. Change it to work out age at a past or future point, such as on an application deadline.
- Read the breakdownYears, months and days together, which is what forms and records usually want.
- Use the exact figure for anything with a thresholdWhere eligibility depends on a specific date, the precise result is what matters, not a rounded year.
Calculating a child’s age in months and weeks
For babies and toddlers, age is usually counted in weeks up to about 3 months and in months up to 2 years, because development checks and vaccination schedules use those units. Enter the birth date and the calculator shows the exact age in years, months and days, plus total weeks and days.
To find an age at a specific date - for a school entry cut-off or a sports age group - change the "age at" date instead of using today.
Key features
- Exact years, months and days rather than a rounded year count.
- Leap years handled correctly, which is where manual counting fails.
- Works to any end date, so you can check age as of a future deadline.
- Runs in your browser - a birth date is personal data and is never transmitted.
- No account and nothing stored between visits.
Common uses
- Filling in a form that asks for exact age in years and months.
- Checking eligibility against an age threshold on a specific date.
- Recording an infant's age in months for medical or developmental milestones.
- Working out how old someone will be on a future date.
- Calculating years of service or tenure from a start date.
Tips for better results
- Check the date format before trusting the result. Day-first and month-first conventions produce plausible but wrong answers.
- For age thresholds, use the exact date rather than the year. Being a day short of eighteen is legally decisive.
- For infants, months is the meaningful unit - "14 months" says far more than "1 year".
- Set a future end date to answer "how old will they be at the wedding" without counting manually.
- To measure between two arbitrary dates rather than from a birth date, the Date Difference tool does the same maths without the age framing.
Mistakes to avoid
- Subtracting birth year from current year, which is wrong for anyone whose birthday has not yet occurred this year.
- Mixing up day-first and month-first date entry, especially between US and international forms.
- Rounding age up when a form asks for completed years - it asks for the birthday you have actually had.
- Assuming leap-day birthdays have a universal legal rule. Jurisdictions genuinely differ between 28 February and 1 March.
- Applying Western age reckoning where a different convention is expected, which can differ by up to two years.
Frequently asked questions
Yes - the calculation properly accounts for leap years when determining exact age or the number of days between dates.
If the tool supports a custom "end date" input (rather than always using today), you can calculate the exact duration between any two dates, not just up to the present.
Years, months and days together - "27 years, 4 months, 12 days" - which is what forms and medical records normally want rather than a rounded year count.
Change the end date from today to whatever date you need. This is how you check eligibility as of an application deadline, or work out how old someone will be at an event.
It varies by jurisdiction. Some treat 28 February as the birthday in non-leap years, others 1 March, and the rule can differ between legal and administrative contexts even within one country. Check the specific rule where it matters.
No. The calculation runs in your browser and nothing is transmitted - which matters, because a birth date is personal data.
Enter your birth date and today; the result includes totals in months, weeks and days as well as years. Paediatric milestones and baby ages are usually counted in weeks and months.
Set the end date to the day you care about - an application deadline, a retirement date or a cut-off for school entry - to see your exact age on that day.
The calculator shows how many days remain until your next birthday, along with the day of the week you were born on - handy for planning a celebration.