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Age Calculator

Calculate exact age from a date of birth, find the difference between any two dates, or compare ages across your whole family or group, with full age gap matrix and PDF download.

Age from Date of Birth
Please select a valid date of birth.
Years
+ Months
+ Days
Total Months
Total Weeks
Total Days
Date Difference
Please select both dates.
Years
+ Months
+ Days
Total Months
Total Weeks
Total Days
CSV / Excel Upload Format
Your file must use these two columns
NameDateOfBirth
Ahmad15/06/1985
Sarah22/03/1990
Liam08/11/2012

First row must be the header exactly: Name and DateOfBirth
Date format must be YYYY-MM-DD for example 1990-03-20
Accepted files: .csv or .xlsx (Excel)
No row limit, upload 2 people or 200, it handles both

📂
Click to upload CSV or Excel file
or enter names and dates manually below
Enter Manually
Please enter a name and date of birth for at least 2 people.
Current Ages, Oldest to Youngest
Age Gap Matrix
PairAge Gap

About the Age Calculator

This Age Calculator gives you an exact breakdown of someone's age from their date of birth, down to years, months and days, plus the total expressed as months, weeks and days. Unlike basic calculators that just subtract years, this tool accounts for varying month lengths and leap years, so the result is always precise regardless of when in the year the birthday falls.

The tool has three modes. The Age from DOB mode is the most commonly used, you enter a date of birth and get the current age broken down in every unit. The Date Difference mode works for any two arbitrary dates, not just birthdays, making it useful for things like calculating how long a contract has been running, how many days until a deadline, or how long a server has been in service. The Group / Family mode is where the tool goes beyond what most calculators offer, it lets you compare ages across multiple people and generates a complete age gap matrix showing the exact difference between every pair.

All calculations run in your browser with no data sent to any server. The group comparison PDF export also runs entirely client-side using jsPDF.

How to Use This Tool

1
Age from DOB: Select the "Age from DOB" tab, pick a date of birth from the date picker, and click Calculate Age. The result shows years, months and days plus totals in weeks and days.
2
Date Difference: Select the "Date Difference" tab, enter a start date and end date. The tool automatically swaps them if you enter them in the wrong order, so you always get a positive result.
3
Group comparison: Switch to the "Group / Family" tab. Enter names and dates of birth manually, or upload a CSV or Excel file. Click Calculate and the tool builds an age ranking and a full age gap matrix.
4
PDF export: After running a group comparison, click Download PDF to get a formatted report with one page per person showing their age and age gaps with every other person in the group.

Example Results

Age from DOB example
FieldResult
Date of birth15 Jun 1985
Age39 years, 10 months, 11 days
Total months478
Total weeks2,081
Total days14,570
Group comparison example
PairAge Gap
Ahmad and Sarah4 yrs, 9 mo
Ahmad and Liam26 yrs, 5 mo
Sarah and Liam21 yrs, 8 mo

Common Use Cases

  • 👨‍👩‍👧‍👦
    Family age records. Compare ages across siblings, parents and grandparents. Useful for family history projects, insurance paperwork or just settling "who is older" arguments.
  • 🏢
    HR and onboarding. Upload a staff CSV and instantly get current ages and age gaps for the whole team. Useful for birthday tracking, benefit eligibility and compliance reporting.
  • 🏫
    School enrolments. Verify that students meet age cutoff requirements by calculating exact age on a specific enrolment date using the Date Difference mode.
  • 📋
    Contract and project timelines. Use Date Difference to calculate exactly how long a project has been running, how many days remain until a deadline, or how long a warranty has been active.
  • ⚕️
    Medical and health records. Calculate a patient's exact age in years and months for documentation, or determine elapsed time since a procedure or vaccination date.

Frequently Asked Questions

How is age calculated exactly?
The calculator uses the calendar date method. It counts complete years first, then complete months within the remaining period, then remaining days. This matches how age is officially recorded in most countries and gives a more accurate result than simply dividing total days by 365.
What CSV format does the bulk upload accept?
Your file needs two columns with the headers "Name" and "DateOfBirth". Dates should be in YYYY-MM-DD format, for example 1990-03-22. Both .csv and .xlsx files are accepted. The tool can handle any number of rows.
Does the tool account for leap years?
Yes. The calculation uses actual calendar dates rather than a fixed 365-day year, so leap years are handled correctly. A person born on 29 February will show their birthday correctly in non-leap years.
Is my data stored or sent anywhere?
No. All calculations and file processing happen entirely in your browser. Nothing is uploaded or transmitted. The PDF is also generated locally using jsPDF.
How many people can I compare in group mode?
There is no hard limit. The tool has been tested with over 200 people. For groups larger than 20 a search filter appears automatically in the age gap matrix to help you find specific pairs quickly.