HII Advanced Age Calculator
Age Calculator — Description & Instructions

Age Calculator — Description & Instructions

Overview

This age calculator calculates age in years, months, and days given a date of birth. You can also use the age calculator to find the exact length of time between two different dates. For convenience, the calculator provides results in many different units of time. You’ll see your age in years, months, and days, and can even break it down further — months and days, total weeks, total days, or even total hours, minutes, and seconds.

Features

  • Instant calculation of age in years, months, and days.
  • Convert age to total weeks, total days, hours, minutes, and seconds.
  • Option to calculate date of birth from a known age (range of possible birth dates).
  • Shows how many days are left until next birthday or a chosen event.
To enable the "calculate DOB from age" feature, go to Settings, select Age and click Save. Input fields for age will appear.

What is My Age?

This chronological age calculator helps you find your exact age. Simply input your date of birth and today’s date to see your current age. You may also use a different end date to find your age on any specific day. At the bottom, the calculator will show how many days are left until your next birthday or event.

How Old is My Child?

Parents of babies and young children often need to count weeks or months to describe their child’s age. The calculator automatically provides age in weeks and months for any age calculation. Just enter a date of birth and click “Calculate”—the age in weeks and months will display instantly, whether you choose today’s date or any date in the future.

How Age is Calculated

This age calculator uses two methods to calculate age:

  1. Years, months, and days (human‑readable format).
  2. Total days (more precise — counts regular years and leap years).

For convenience the calculator sometimes uses standard averages (years = 365 days, months = 30.4167 days). For exact results it counts every regular year (365 days), leap year (366 days), and partial months/days between the two dates.

Example

Born on November 15, 2006, age on March 10, 2026 is calculated as:

19 years, 3 months, 23 days (subtract days, borrow months if needed; subtract months, borrow years if needed; subtract years).

How Many Days Until...?

To calculate by hand how many days until a specific date, add the number of full months (using the table below) and sum the number of days in the partial months. Remember to consider leap years and months with 28, 30, or 31 days.

Number of Days per Month

  • January: 31
  • February: 28 (regular year), 29 (leap year)
  • March: 31
  • April: 30
  • May: 31
  • June: 30
  • July: 31
  • August: 31
  • September: 30
  • October: 31
  • November: 30
  • December: 31

How to Calculate Age from Birthdate in Excel

Track your age or days since any event using Microsoft Excel. Use DATEDIF to compute years, months, and days:

Years: =DATEDIF(A1, TODAY(), "Y")
Months: =DATEDIF(A1, TODAY(), "YM")
Days: =DATEDIF(A1, TODAY(), "MD")

Combine: =CONCAT(A2, " years, ", A3, " months, ", A4, " days")

Privacy & Notes

Our age calculator is fast, accurate, and secure. It works for people, pets, objects, companies, and any event where time measurement matters. No login required.