How the age is calculated
The calculator counts whole years since the date of birth, then the months and days since the most recent birthday, using your device's date. So someone born on May 12, 2018 is 8 years, 4 months, and 7 days old on September 19, 2026. The birthday counts as the day someone turns a year older, and nothing you enter leaves your browser.
Born on February 29? In years without a February 29, the calculator counts the birthday on February 28, which is what many leap-day babies celebrate.
Next birthday and days until it
Below the age you'll find the date of the next birthday, the age it brings, and how many days away it is. If the birthday is today, it says so. For a live countdown you can share with family, open the birthday countdown with the same date.
Want to keep it in your Mac's notch?
Notchiko keeps birthdays, ages, countdowns, and more right where you can see them. Add a birthday and its card reads “23 days · Emma turns 9”, with the exact age in Settings. See Age & Birthday in Notchiko.