Age Calculator
Age Calculator reports the number of fully completed calendar years between a birth date and today in the browser's local calendar. It subtracts years, then adjusts when this year's birthday has not yet occurred. It is a convenient estimate, not identity verification or a legal determination.
Runs locally — files stay on your deviceWhy is age not simply the current year minus birth year?
Because one year must be subtracted when the birthday has not yet occurred in the current calendar year.
Completed age changes on the birthday
Completed years equal current year minus birth year, reduced by one if today's month and day precede the birthday month and day.
How it works
Enter the birth date. The tool compares it with today's local date and returns fully completed years.
Key concepts
Only completed years count
Partial progress toward the next birthday is not rounded up.
Today comes from the local browser
The result can change around midnight depending on local date.
When to use it
- Check an approximate current age.
- Verify a birthday-based year count.
- Avoid manually deciding whether this year's birthday passed.
When not to use it
- Do not use it as proof of identity.
- Do not assume every jurisdiction treats leap-day birthdays identically.
- Do not use it for age at a different historical date.
Worked examples
Birthday already passed
- Input
Born 2000-01-10; today after January 10, 2026- Expected output
26
The 2026 birthday has occurred.
Birthday still ahead
- Input
Born 2000-12-10; today before December 10, 2026- Expected output
25
Only 25 full years are complete.
On the birthday
- Input
Birthday matches today's month and day- Expected output
New completed age
The next year becomes complete on that date.
Common mistakes
Subtracting years only
That overstates age before the birthday. Correction: Compare month and day as well.
Treating the output as verified
The tool accepts any entered date. Correction: Use authoritative documents where proof is required.
Ignoring leap-day policy
Legal recognition may vary in non-leap years. Correction: Consult the applicable rule for formal decisions.
Best practices
- Use the correct local birth date.
- Confirm today's date on the device.
- Use official verification for regulated age checks.
Related operations and differences
Add Days to Date
Choose Add Days to Date when you need to find a future date after adding days.; use Age Calculator specifically for age.
Add Months to Date
Choose Add Months to Date when you need to add calendar months using local browser time.; use Age Calculator specifically for age.
Add Weeks to Date
Choose Add Weeks to Date when you need to add a number of weeks to a date.; use Age Calculator specifically for age.
Business Days Calculator
Choose Business Days Calculator when you need to count weekdays between two dates.; use Age Calculator specifically for age.
Date Difference Calculator
Choose Date Difference Calculator when you need to count calendar days between two dates.; use Age Calculator specifically for age.
Date to Unix Timestamp
Choose Date to Unix Timestamp when you need to convert a date and time to Unix seconds.; use Age Calculator specifically for age.
Limitations and privacy
- Reports completed years only.
- Uses today's local browser date.
- No jurisdiction-specific leap-day or legal-age rule is applied.
Dates and calculations stay in this browser and are not uploaded.
Frequently asked questions
Does it round age up?
No.
What date is age measured against?
Today's local browser date.
Can it verify someone's age?
No.
How are leap-day birthdays handled?
The browser calendar is used; legal rules may differ.