How age calculations work
What is an age calculator?
An age calculator measures the time between a person’s date of birth and a chosen date. It helps you understand age in a way that matches the calendar, including years, months and days rather than a rough estimate.
How do I calculate age from a date of birth?
Enter your birth date and the date you want to calculate as of. The calculator counts the full calendar years, then the remaining calendar months and days. This is more precise than subtracting years alone.
How is age calculated in years, months and days?
The calculation works by first counting full years between the dates, then full months remaining, and finally the leftover days. For example, a person born on March 15, 2004, and measured on November 10, 2026, is 22 years, 7 months and 26 days old.
How do leap years affect age?
Leap years add one extra day to February, which changes the total number of days lived. The calculator handles leap years correctly so birthdays and age totals stay accurate across February 29 birthdays and annual transitions.
How do I calculate age on a specific date?
Select the date you want to use in the “Calculate age as of” field. This lets you calculate exact age for a historical date or a future date, as long as the birth date remains valid.
What is a baby age calculator?
A baby age calculator is designed for infants and toddlers, where age is often expressed in weeks and days during the first months of life. It helps parents measure age more naturally than a general adult age calculator.
How do I calculate my baby’s age in weeks?
Count the total number of calendar days from the birth date to the chosen date, then divide that number by 7. The result shows the completed weeks and any remaining days.
How do I calculate my baby’s age in months?
For most babies, age in months is calculated in calendar months, not a simple division of total days by 30. This keeps the result aligned with real month lengths and birthdays.
Why is baby age often expressed in weeks during early infancy?
In the first months, an infant’s age changes quickly from week to week. Smaller units such as weeks and days make it easier to follow growth and milestones in a way that feels natural for parents.
What is the difference between chronological age and corrected age?
Chronological age is the age measured from the actual birth date. Corrected age is an adjustment used for some premature babies. It is an estimate, not a medical assessment, and should be interpreted with a pediatrician.
Frequently asked questions
How do I calculate my exact age?
Enter your date of birth and the date you want to calculate as of. The calculator uses calendar-based math, so it can show your age in years, months and days without approximating months by days.
How many days have I lived?
The total days lived is the number of calendar days between your birth date and the chosen date. This includes the full days that have passed and excludes any incomplete current day.
How do I calculate my baby's exact age?
Enter the baby's date of birth and the date to calculate as of. The baby calculator can display age in years, months and days or in weeks and days, which is especially useful during the first year.
What is corrected age for premature babies?
Corrected age is a rough estimate used for some premature babies to compare development against expected age. It is not a diagnosis and should be discussed with a pediatrician for interpretation.