Enter a date of birth and this calculator gives the exact age in years, months and days – handy for forms, school admissions and official paperwork where ‘about right’ is not enough.
Age Calculator
Total days:
See the manual method in our guide: How to Calculate Age from Date of Birth Exactly
How to use the Age Calculator
- Enter the date of birth in the "Date of birth" box. Use the date picker, or type the date in the format your browser shows.
- Leave the "Age at date" box as today, unless you want the age on a different day — a school cut-off date, a retirement date, or a past event.
- Press "Calculate Age".
- Read the exact age in years, months and days, plus the total number of days below it.
How it works
The calculator counts in the same way people do. First it counts the whole years: one full year is added each time the birthday has passed by the "age at" date. Then it counts the whole months that have passed since the last birthday. Whatever is left over is counted in days.
It also counts the total number of days between the two dates, every single one, including the extra day in each leap year. That is why the total days figure is exact rather than a rough estimate worked out from years alone — two people who are both "26 years old" can have lived a different number of days, depending on where the leap days fell.
Worked example
Take someone born on 15 June 2000, and ask for their age on 21 October 2026. Enter 15 June 2000 as the date of birth and 21 October 2026 as the age at date.
Their 26th birthday fell on 15 June 2026, so the whole years come to 26. From 15 June to 15 October is 4 whole months, and from 15 October to 21 October is 6 more days. The exact age shown is therefore 26 years, 4 months and 6 days. The total days figure is 9,624 — every day from the date of birth up to the date you chose, leap days included.
Common mistakes
- Typing the wrong year, such as 1999 instead of 1990. A one-digit slip changes the result by years, so it is worth a second look at the date before pressing the button.
- Forgetting that the "age at date" box is set. If you changed it earlier to test a future date, the age shown is for that date, not for today.
- Counting the year you are currently in as a completed year. Someone who turns 26 this year is 26, even though they are living their 27th year.
- Assuming every year has 365 days when working out total days by hand. Leap years add days, which is why hand sums and this calculator can differ slightly.
Frequently asked questions
Q: What happens if I leave the "Age at date" box alone?
It stays set to today, so the calculator shows the current age. Change it only when you want the age on a specific past or future date.
Q: Can I find out how old someone will be on a future date?
Yes. Enter the future date in the "Age at date" box — useful for school admission cut-offs, exam eligibility, licence renewals or retirement planning, where age on one particular day is what counts.
Q: Why does the total days figure matter?
Some forms, insurance policies, and official records ask for age in days for babies and young children, because at that age a few weeks make a real difference. The total is also handy for milestones, such as the day someone turns 10,000 days old.