Calculate your exact age or the difference between any two dates in years, months, weeks, days, hours, minutes, and seconds.
| Stage | Age Range |
|---|---|
| Infant | 0 – 1 year |
| Toddler | 1 – 3 years |
| Child | 3 – 12 years |
| Teenager | 13 – 17 years |
| Young Adult | 18 – 35 years |
| Middle Aged | 36 – 55 years |
| Senior | 56 – 79 years |
| Elderly | 80+ years |
Age is calculated by finding the difference between a date of birth and a reference date — usually today. The standard method counts the number of complete years first, then the remaining months, then the remaining days. This is why a person born on January 31 turns one year older on January 31 of the following year, not 365 days later (since not every year has 365 days — leap years have 366).
In most Western countries, a person's age increases on their birthday each year. In South Korea, the traditional system (Korean age) counts everyone as 1 year old at birth and adds a year on January 1 every year — meaning a person born in December is considered 2 years old just one month later in January. Japan formerly used a similar system but has largely adopted the Western method for official purposes.
Leap years add one extra day (February 29) every four years, with exceptions for century years not divisible by 400. People born on February 29 (leap day) technically only have a birthday every four years — they commonly celebrate on February 28 or March 1 in non-leap years. Age calculators account for leap years when counting total days.
Chronological age is the number of years since birth — what this calculator computes. Biological age refers to how old the body appears based on health markers. Psychological age refers to how old a person feels or acts. Mental age compares cognitive ability to typical development at a given age.
Yes — the Date Difference mode calculates the time between any two dates. You can use it to find the age of a business, a building, a marriage, a historical event, or anything else with a known start date.