How years, months and days are counted
Whole years are the birthdays you have had. The months are the full months since your last birthday, and the days are what is left over. Because months have 28 to 31 days, the leftover days are counted from the same date in the previous month. Someone born on 31 August 1990 is, on 15 November 2026, 36 years, 2 months and 15 days old: 31 August to 31 October is 2 months, and 31 October to 15 November is 15 days.
Different calculators can differ by a day on dates near the end of a month. Official forms usually only ask for whole years, where every method agrees.
Finding the birth year from an age
An age alone gives two possible birth years. Someone who is 30 in 2026 was born in 1996 if their birthday has already passed this year, or in 1995 if it has not. The rule is simple: birth year = current year − age, minus one more if this year’s birthday is still to come. Enter a likely birth date here and check the result to confirm.
Chronological age for school and test reports
Psychologists, speech therapists and teachers need a child’s exact chronological age on the test date to look up scores. Enter the date of birth, set “Age on date” to the day of the test, and read the years, months and days. Reports often write it as 8;4 for 8 years and 4 months. Some test manuals round 15 or more leftover days up to the next month and others never round, so follow the manual for the test you are scoring.
Age in months, weeks and days
Babies are described in weeks and then months, so a 14-month-old is easier to picture than a 1-year-old. The totals under your age show the same life in months, weeks, days and hours, and the milestones list days such as your 10,000th day, which falls at about 27 years and 4 months. Totals count every calendar day, leap days included.