How to find your birth year
Your birth year is the current year minus your age. There are two possible years: if you've already had your birthday this year, it's current year − age; if not, it's one year earlier. For age 25 in 2026, that's 2000 or 2001.
A worked example makes it clear. Someone who is 40 in 2026 and whose birthday falls in March has already had it by May, so they were born in 1986 (2026 minus 40). Someone else who is also 40 in May 2026 but has a birthday in November has not had it yet this year, so they were born in 1985 - one year earlier - and will turn 41 in November.
Put simply: birth year = current year minus age if the birthday has passed, and current year minus age minus 1 if it has not.
Pair this with the age in days calculator when you need the fuller picture.
How to use this calculator
Enter your current age in years. The result shows both possible birth years. To find an exact age from a known birth date instead, use the age calculator.
This is why two forms can seem to disagree by twelve months. Age is a moving number that changes once a year; a birth year is fixed. If you need an age counted in months and days rather than whole years, start from the full date instead.
Common checks people run here: confirming a birth year for a passport or membership form, working out which school year or generational cohort someone falls into, and sense-checking a year quoted in an old record. For anything official, use the documented date of birth - an age alone will always leave two candidates.
The days between dates calculator handles the closely related case.
Frequently asked questions
- How do I find my birth year from my age?
- Subtract your age from the current year. The exact year depends on whether your birthday has happened yet this year.
- Why are there two possible years?
- Because your age covers part of two calendar years — before and after your birthday.
- What year was I born if I'm 25?
- In 2026, either 2000 (if your birthday has passed) or 2001 (if not).
- How do I get an exact birth year?
- Use your full date of birth. Knowing just the age leaves two possibilities.
- What if I was born on 29 February?
- The arithmetic is identical: subtract your age from the current year. In non-leap years most people born on 29 February treat 28 February or 1 March as their birthday, which only affects which of the two candidate years applies during those few days.