Birthday Calculator
Find what day you were born and days until next birthday.
You might also need
How It Works
Calculates exact age from birth date and shows days until next birthday. Accounts for leap years.
Formula
Day of week from dateQuick Reference
Common calculations — results you can verify instantly.
Age in days
30 years × 365.25
~10,957 days lived
Next birthday
Days until
Shows countdown
Born in leap year
Feb 29 birthday
Celebrate Feb 28 or Mar 1
Tips & Shortcuts
Useful for verifying age for legal documents.
Age is one less if birthday has not occurred yet this year.
Common Mistakes
Only subtracting birth year from current year
If birthday has not occurred this year age is still last years number.
Feb 29 birthdays in non-leap years
Legally celebrate Feb 28 or March 1 depending on jurisdiction.
Frequently Asked Questions
Resets each year on birthday showing days until next one.
September 9 statistically in US.
Related Calculators
Business Days Calculator
Count working days between two dates, excluding weekends.
Day Counter
Count days remaining until any future date.
Percentage Calculator
Find X% of Y, X is what % of Y, or percentage change.
Percent Off Calculator
Find the sale price after a percentage discount.
Unix Timestamp Converter
Convert Unix timestamps to human-readable dates and back.
Time Zone Converter
Convert times between any two time zones worldwide.