How to use the age calculator
- Date of birth, pick the day you (or whoever you’re checking) were born.
- Age at date, leave it on today to get the current age, or change it to any other date.
- Read off your age in years, months and days and your total days lived, they update the moment you change a date.
Why “years, months and days” instead of a decimal
Saying someone is “31.7 years old” is rarely what people mean. The calendar isn’t made of equal-length months, so a true age has to borrow correctly: if the day-of-month hasn’t been reached yet this month, we take the days from the previous month’s real length, and if the birthday month hasn’t arrived this year, we drop a year and add the twelve months back. That’s exactly how you’d count an age out loud, “31 years, 8 months and 12 days”, and it’s what this tool gives you. Leap years are respected too, so a 29 February birthday and the days around it stay accurate.
What you can use it for
- Birthdays & milestones: see exactly how long until a round number, or how many days you’ve been alive.
- Forms & eligibility: confirm an age as of a specific cut-off date, not just today.
- Anniversaries & record-keeping: work out the age of anything with a start date, a pet, a contract, a project.
Frequently asked questions
Why does it say my birth date is in the future?
The birth date you entered is later than the “age at” date. Make sure the birth date comes first, or move the “age at” date forward.
Does the total-days figure include today?
It counts whole days between the two dates. On your birthday the day count resets to zero, and the total grows by one for each full day that passes.
Can I calculate age between two past dates?
Yes, set both the birth date and the “age at” date to any dates you like to measure the gap between them.