Date & Time
Age Calculator
Work out an exact age in years, months and days from any date of birth, plus the days until the next birthday.
Updated 24 Sep 2026
You are 36 years, 5 months and 1 days old — 13,303 days in total. Your next birthday is in 211 days.
Enter a date of birth and, optionally, a date to measure to. The calculator returns the exact age in years, months and days, the total number of days lived, and how long until the next birthday.
What is the Age Calculator?
An age calculator converts a date of birth into elapsed time, correctly handling months of different lengths and leap years.
You can measure to today or to any other date, which is useful for eligibility cut-offs — school admissions, exam age limits and scheme qualifying dates.
How to use the Age Calculator
- Enter the date of birth.
- Leave the second date as today, or set a different date to measure to.
Formula
Months = whole months after subtracting years
Days = remaining days after subtracting years and months
Total days = complete calendar days between the dates,
counting each leap day that falls in the interval
Ages cannot be computed by dividing total days by 365.25 — that gives an approximation that drifts. Proper date arithmetic walks the calendar, which is what this calculator does.
How the calculation works
The calculation finds the difference between two calendar dates directly. February's variable length and leap years are handled by the calendar itself rather than by an averaging assumption.
The next birthday is found by moving the birth date to the current year and, if that has already passed, adding a year.
Worked example
Born 15 May 1990, measured on 21 August 2026:
- Age: 36 years, 3 months and 6 days
- Total days lived: 13,247
- Next birthday: 267 days away
Uses and benefits
- Check eligibility against an exact cut-off date.
- Fill in forms that ask for age in completed years.
- Work out age at a past or future event.
Frequently asked questions
By walking the calendar rather than dividing days by an average year length. The calculator counts complete years, then complete months from that point, then the remaining days — which is how official forms define completed age.
Yes. Because it uses real calendar arithmetic rather than an average of 365.25 days, every leap day in the interval is counted correctly.
Yes. Set the second field to any future date to find your age then. This is useful for checking eligibility cut-offs for exams or schemes.