How this calculator works
The calculator subtracts the date of birth from the as-of date. It borrows days from the previous month and months from the year when needed, so the answer is completed years, months and days. Total days lived is the exact number of calendar days between the two dates.
Age from date of birth
Age = as-of date − date of birth, expressed as years, months and days.
Days to next birthday = next occurrence of the birth date − as-of date. A 29 February birthday falls on 1 March in non-leap years.
Worked example
Date of birth 15 June 1995, as of 6 November 2026: 31 years 4 months 22 days. That is 11,467 days lived, the person was born on a Thursday, and the next birthday is Tuesday, Jun 15, 2027, 221 days later.
How to use this calculator
- Enter the date of birth.
- Leave Age as of empty to use today, or choose another date.
- Select Calculate to see age, days lived and the next birthday.
Frequently asked questions
How do I calculate age from date of birth?
Subtract the birth date from the date you are measuring to. Count completed years first, then leftover months and days.
Is this the same as the Age Calculator?
The results are consistent. This page is laid out around a date of birth and adds the birth weekday and next-birthday countdown. The Age Calculator offers a general age and date-difference view.
How are leap-year birthdays handled?
A 29 February birth date is treated as 1 March in years that are not leap years when finding the next birthday.
Can I check age on a past or future date?
Yes. Enter any date in the “Age as of” box, for example an exam cut-off date.
Ages are calculated on the Gregorian calendar. Legal age rules for specific schemes or exams can use different cut-off conventions.
Related searches: date of birth calculator, birthday calculator, dob calculator, birth calculator, age calculator by dob.
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