Age Calculator

Age is measured the way people naturally count it: in whole years, then the leftover whole months, then the leftover days. The calculator starts from your date of birth and counts complete years up to the target date, then complete months, then the remaining days. Because calendar months are different lengths (28 to 31 days) and leap years add a 29th of February, a purely decimal “age = days ÷ 365” shortcut drifts by a day or more — so this tool counts real calendar units instead. When a birth day does not exist in a shorter month (for example the 31st, or the 29th of February in a common year), the month is completed on that month’s last day, which is why a 29 February birthday is counted on 28 February in common years and on 29 February in leap years.

• Calendar and leap-year rules follow the Gregorian calendar (in use since 1582): a leap year is divisible by 4, except century years, which must be divisible by 400.
• Western (tropical) zodiac date ranges use the commonly published sun-sign boundaries; exact cusp dates can shift by a day between years.
• Chinese zodiac animals follow the 12-year cycle by calendar year; because the Chinese New Year falls in late January or February, people born in that window may belong to the previous animal.
• Heartbeat, breathing and sleep figures are illustrative averages (about 80 beats and 16 breaths per minute, and roughly one third of life asleep) and vary by person, age and activity.
• Orbital distance uses Earth’s average path length of roughly 940 million kilometres per year.