How is age calculated?
Age is the difference between your date of birth and a target date, accounting for the varying length of months and for leap years. This is why dividing total days by 365 is not accurate.
The correct method subtracts years first, then months, then days, borrowing from the larger unit where needed — exactly like ordinary subtraction.
Leap years These occur every 4 years (excluding century years not divisible by 400), giving February 29 days. The calculator accounts for this automatically.
When exact age matters
- Official applications: jobs and university places with age limits.
- Medicine: drug dosages and vaccination schedules sometimes depend on age in months.
- Insurance and pensions: calculating remaining terms precisely.
- Sport: competition age groups are set by a specific cut-off date.
Frequently asked questions
How do I calculate my exact age?
Enter your date of birth and the tool works out the difference to today in years, months and days, accounting for leap years and differing month lengths.
Why not just divide total days by 365?
Because a leap year has 366 days and months vary between 28 and 31 days. Dividing by 365 gives an approximation that can be off by several days.
Can I calculate age at a future date?
Yes. Change the "calculate as of" field to any date, past or future.
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