Explore our age calculation guides to understand how age can be calculated from a date of birth, how common age formulas work, and how to handle different calculation methods and special cases. Whether you want to calculate age manually, use Microsoft Excel or Google Sheets, understand a leap-year birthday, or learn what chronological age means, choose the guide below that matches what you need.
Learn How to Calculate Age
How to Calculate Age
If you want to understand the basic process of calculating someone’s age from their date of birth, start here. This guide explains how to determine age in completed years and how months and days can be included when a more exact age is needed.
Learn how to calculate age from a date of birth.
Age Calculator Formula
Age calculation involves more than simply subtracting the birth year from the current year. This guide focuses specifically on the calculation logic and formula used to determine an accurate age from a birth date and a target or reference date.
See the age calculator formula and how it works.
Calculate Age in Spreadsheets
If you work with dates in a spreadsheet, you can calculate age automatically instead of working it out manually for every person. We have separate guides for the two most commonly used spreadsheet platforms.
Calculate Age in Excel
Learn how to calculate age from a date of birth in Microsoft Excel. The guide covers practical spreadsheet methods for working with birth dates and calculating age in the format you need.
Learn how to calculate age in Excel.
Calculate Age in Google Sheets
Google Sheets can also calculate age automatically when dates of birth are stored in a spreadsheet. This guide explains the Google Sheets approach separately so you can use formulas suited to that platform.
Learn how to calculate age in Google Sheets.
Special Age Calculation Cases
How Age Is Calculated for Leap-Year Birthdays
People born on February 29 have a birth date that does not appear every calendar year. Our dedicated leap-year guide explains how this affects age calculation and why February 29 birthdays require special consideration in non-leap years.
Read the guide to age calculation for leap-year birthdays.
Understand Chronological Age
Chronological Age Explained
Chronological age describes age based on the time that has passed since a person’s date of birth. If you have seen the term used in education, assessments, records, or age calculations and want to understand what it means, this guide covers the concept in more detail.
Learn what chronological age means and how it is determined.
Which Guide Should You Read?
Use the table below to go directly to the age calculation guide that best matches your question.
| Your Goal | Recommended Guide |
|---|---|
| Learn how to calculate age manually | How to Calculate Age |
| Understand the calculation formula | Age Calculator Formula |
| Calculate age in Microsoft Excel | Calculate Age in Excel |
| Calculate age in Google Sheets | Calculate Age in Google Sheets |
| Understand a February 29 birthday | Leap-Year Birthday Age Calculation |
| Understand chronological age | Chronological Age Explained |
Age Calculation Guide FAQs
Which guide should I use to calculate age from a date of birth?
Start with our How to Calculate Age guide. It is the best starting point if you want to understand the general calculation process.
Where can I learn the exact age calculation formula?
See the Age Calculator Formula guide for the calculation logic behind determining age from two calendar dates.
Which guide should I use if the date of birth is February 29?
Use our leap-year birthday guide, which is dedicated specifically to age calculations involving a February 29 date of birth.
Can I calculate age automatically in a spreadsheet?
Yes. Choose either our Excel age calculation guide or our Google Sheets age calculation guide, depending on the spreadsheet platform you use.