How your age is calculated
Your age is the time elapsed between your date of birth and today. This calculator works it out the way people actually count age — in whole years, then the leftover months, then the leftover days — rather than dividing by an average year length. It does this by subtracting the calendar components and borrowing from the previous month when the days run negative, which keeps the result accurate across months of different lengths and leap years. The total-days figure counts every single day you have been alive, including the extra days from every leap year you have lived through, so it is exact rather than an approximation.
Why months and days matter, not just years
Rounding age to whole years hides useful detail. The exact breakdown in years, months and days matters for official forms, visa and pension eligibility, school cut-off dates, and medical dosing for children where a few months changes the guidance. It is also the figure people want for milestone birthdays and anniversaries. Because this calculator counts real calendar months rather than assuming every month is 30 days, the months-and-days portion lines up with how a registrar or doctor would record your age, not a rough estimate.
Counting in weeks, days and beyond
Expressing age in different units is surprisingly handy. New parents track a baby's age in weeks and days; fitness and habit trackers count total days; and curious milestones — your ten-thousandth day, for instance — fall on dates you would never guess. The total-weeks figure divides your total days by seven, and the total-days figure counts every day since birth. Switching between units turns an abstract number into something you can plan around, celebrate, or simply find interesting.
Leap years and time zones
This calculator counts the actual days between two dates, so leap days are included automatically — no need to adjust for them. It uses your device's current date for 'today', which means the result reflects your local date. For the cleanest result, enter your birth date in full; partial or invalid dates cannot be measured. Age is one of the few calculations where the calendar, not arithmetic, decides the answer, and this tool follows the calendar exactly.
Frequently asked questions
How do I calculate my exact age?
Subtract your date of birth from today's date in years, months and days. This calculator does it precisely, borrowing days from the previous month so the result matches how age is officially recorded.
Does this account for leap years?
Yes. It counts the actual number of calendar days between your birth date and today, so the extra day in each leap year is included automatically.
What is my age in total days?
It is the count of every day you have been alive, including leap days. The calculator shows this alongside your age in years, months, weeks and days.
Why does the months-and-days part change between dates?
Because calendar months have different lengths. The calculator counts real months rather than assuming 30 days each, so the leftover days adjust depending on the month.