How is age calculated?

Enter a 'from' date (typically a date of birth) and a 'target' date (defaults to today). The calculator returns the difference in years, months, and days using the standard calendar convention — so on someone's 30th birthday, it reads exactly 30 years, 0 months, 0 days.

What does 'age at end of year (31st Dec)' mean?

It is the age the person will be on 31 December of the year the target date falls in. Many athletics age-group competitions use this figure to decide which category an athlete competes in.

Can I calculate a date from an age?

Yes — switch to Calculate Date mode. Enter a date and an age, choose whether the date is the 'from' date (result is target) or the 'target' date (result is from), and the calculator returns the matching date.

Age Calculator - Athletics Utils

Calculate:

Calculate Age: from two dates, calculate the age between them. Calculate Date: from a date and an age, calculate the matching date.

From date Usually a date of birth.

Target date Defaults to today. The date to measure age on.

Calculation History

Mode	Input	Result

How to Use

Calculate Age mode:
1. Enter a From date (typically a date of birth)
2. Adjust the Target date if you need an age on a day other than today
3. The result updates automatically and shows the exact age in years, months, and days

Calculate Date mode:
1. Enter a date
2. Choose whether that date is the From Date (result = date + age) or the Target Date (result = date − age)
3. Enter an age in years, months, and days and the matching date is calculated instantly

Add to History & Share:
• Results compute automatically — use Add to History when you want to keep one for reference
• The Share button copies a link that re-opens the calculator with the same inputs

Age at end of year (31 Dec)

Underneath each Calculate Age result is a second line showing the age the person will be on 31 December of the target year. Most national and international athletics federations assign athletes to age groups (U15, U17, U18, U20, etc.) based on their age on the 31 December of the competition year, so this value is often more relevant than the literal age on competition day.

Calculate Date mode

Calculate Date mode answers questions like "what date is 25 years, 3 months, and 10 days after 5 April 2034?" or "if I'm 32 years and 4 months old today, when was I born?" — useful for working out the cut-off dates for an age-group competition.

Related Calculators

Plan training paces with the Pace & Speed Calculator, add or multiply times with the Time Calculator, or convert performances into points with the World Athletics Score Calculator.