Age Calculator & Date Engine

Q: How do working days get counted?

The tool counts Monday through Friday between your start and end dates. Any holidays you supply in YYYY-MM-DD format are also excluded.

Q: Can I calculate a future date by adding days?

Yes. Use the Add / Subtract Days tab to project a base date forward or backward by any number of days.

Q: What does the next birthday countdown do?

After calculating your exact age, the tool shows how many days remain until your next birthday or a Happy Birthday message if today is the day.

Q: Why do total months and years differ slightly from other tools?

This tool uses true calendar arithmetic instead of assuming every month is 30 days, which is why totals may differ by a day or two from averaged calculators.

Q: Is this Age Calculator free to use?

Yes, the UD Tools Age Calculator and Date Engine is 100% free with no signup, no download, and no limits.

A single, powerful date engine that goes beyond a normal age calculator. Get your exact age in years, months, weeks, days, hours and minutes — plus date differences, next birthday countdown, working days, and future/past date math, all in one place.

Quick Answer: Enter your date of birth to instantly see your exact age (years, months, days, hours, minutes), total days lived, and days until your next birthday. Switch tabs to calculate date differences, add or subtract days, and count working days between two dates.

Date of Birth

Calculate As Of (optional)

You Are

—

Years

Months

Days

Total Months0
Total Weeks0
Total Days Lived0
Total Hours0
Total Minutes0

From Date

To Date

Total Difference

—

Days0
Weeks0
Months (approx)0
Hours0
Minutes0

Person 1 — DOB

Person 2 — DOB

Age Gap

—

Total Days Apart0
Total Months Apart0

Base Date

Number of Days

Operation

Resulting Date

—

Start Date

End Date

Holidays (optional, comma-separated YYYY-MM-DD)

Working Days

—

Total Days0
Weekends0
Holidays Excluded0

How to Use the Age Calculator

1Pick your tab — Exact Age, Date Difference, Age Between 2, Add/Subtract Days, or Working Days.
2Enter your date(s) using the built-in date picker. All calculations happen in your browser.
3Click Calculate to instantly see the full breakdown — years, months, days, hours, minutes and more.
4Copy or reset your result. Nothing is stored or uploaded — your data stays private.

Features at a Glance

Exact Age

Get age in years, months, weeks, days, hours and minutes with pinpoint accuracy.
Date Difference

Calculate the exact gap between any two dates in multiple units instantly.
Compare Two People

Find the age gap between two people down to the exact day.
Date Math

Add or subtract days from any date to find future or past dates instantly.
Working Days

Count working days excluding weekends and your custom list of holidays.
100% Private

All calculations run in your browser. No data is uploaded, tracked, or stored.

Common Mistakes & Tips

Always use the format YYYY-MM-DD when typing holidays — other formats may be ignored.
Your date of birth cannot be in the future — the tool will show an error if it is.
Leave the "As Of" field blank to use today's date automatically for exact age.
Working days count Monday to Friday. Add public holidays manually for accurate business-day math.

Frequently Asked Questions

How is my exact age calculated?

Your exact age is calculated by comparing your date of birth to today's date (or a custom "as of" date). The tool subtracts years, months and days using a real calendar algorithm that accounts for leap years and variable month lengths, giving you a precise breakdown down to the minute.

Does this tool work offline or share my data?

All calculations run 100% in your browser using vanilla JavaScript. No dates are ever sent to any server, stored in a database, or tracked. Once the page has loaded, most functions continue to work even without an internet connection.

How accurate is the age between two people feature?

It computes the exact number of days between the two dates of birth and translates that into years, months, and days. This is more accurate than simply subtracting birth years, especially when the two people were born only a few months apart.

How do working days get counted?

The tool iterates through every day between your start and end date, counting only Monday through Friday as working days. If you provide a list of holidays in YYYY-MM-DD format, those dates are also excluded from the working-day count.

Can I calculate a future date by adding days?

Yes. Use the "Add / Subtract Days" tab, choose a base date, enter the number of days, and select "Add" to project into the future or "Subtract" to go back in time. The result shows the resulting date along with the day of the week.

What does the "next birthday" countdown do?

After calculating your exact age, the tool automatically shows how many days remain until your next birthday. If today is your birthday, it displays a special "Happy Birthday" message instead of a countdown.

Why do total months and years differ slightly from other tools?

This tool uses true calendar arithmetic (real months and leap years) instead of assuming every month is 30 days. Some other calculators use averaged values, which is why totals can vary by a day or two. This tool's method matches how legal and official age is usually determined.

Is this Age Calculator free to use?

Yes, the UD Tools Age Calculator & Date Engine is 100% free with no signup, no download, and no limits. You can use it on your phone, tablet, or desktop as many times as you want.

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Developed By

Muhammad Usman

Founder, Developer & CEO

Building free, fast, and practical web tools for everyday users — from image converters to text utilities, designed to solve real problems without ads getting in your way.

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