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Age Calculator

Calculate your exact age down to the day. Works for any birth date and any target date – see results in years, months, days, weeks, hours, minutes, and seconds. Free, no sign-up required.

Last revised 25 September 2026

By Team GlobalCalqulate · About our editorial standards

Date Information

Date of Birth

Your birth date.

Target Date

The date to calculate age at (defaults to today).

Time of Birth (HH:MM)

Exact time of birth for precise age calculation.

Target Time (HH:MM)

Exact time for precise age calculation.

Display Format

Methodology

Formula:: Calendar age
Content last updated:: September 2026
Scheduled re-verification:: September 2027

Calculation type: Exact calculation.

Formula & methodology

Formula used

Calendar age

years, then months, then days are taken in turn from the date difference

Age is counted the way people count it: whole years first, then whole months, then the days left over — borrowing from the previous month when the day of month has not yet been reached.

Total elapsed units

total days = (target − birth) ÷ 86,400,000 ms;  weeks = days ÷ 7

Absolute elapsed time, derived from the millisecond difference between the two dates.

Variable definitions

Symbol	Meaning	Unit
birth date	Date of birth. the starting date	date
target date	Target date. the date to measure age at; defaults to today	date

Step-by-step calculation

1. Enter the date of birth
Set a target date to find age at some other moment.
2. Include the time of day if you need it
Without it both dates are treated as midnight.

Limitations

Ages are computed on calendar dates (year, month, day) exactly as written, so the result does not depend on your time zone. If a birth time is included it is treated as local clock time at both moments, and a birth in a different time zone can shift the elapsed hours.
Months are of unequal length, so 'months' in the breakdown means calendar months, not a fixed number of days. When an anniversary day does not exist in a month (born on the 31st, or 29 February), it is taken on that month's last day: a 31 January birth reaches one month on 28 February, and a 29 February birthday is observed on 28 February in non-leap years. Some legal systems use 1 March instead.
Decimal age (Years Only) is the whole years plus the fraction of the way through the current year of age.
The target date cannot precede the birth date; the calculator reports this rather than returning a negative age.

This page is educational. It applies the formula described above to the figures you enter and shows the arithmetic behind the result. The output is only as good as the inputs and the assumptions listed here, and it is general information rather than advice about your particular situation.

Help & FAQs

Frequently Asked Questions

Clear answers to common questions to help you use this calculator confidently.

How do I calculate my exact age in years, months, and days?

Tap to view the answer

Enter your date of birth and a target date (or leave it as today). The calculator subtracts the birth date from the target date using calendar rules that account for leap years and varying month lengths. It then breaks the result into years, months, and days — plus weeks, hours, minutes, and seconds if you include the time.

Does the age calculator account for leap years?

Tap to view the answer

Yes. The calculator counts every leap year between your birth date and target date. It correctly handles February 29 — so if you were born on a leap day, your age is calculated using February 28 or March 1 in non-leap years as appropriate.

Can I calculate how old I will be on a future date?

Tap to view the answer

Yes. Set the target date to any date up to the year 2099. The calculator works for both past and future dates — useful for planning milestones, birthday countdowns, or determining eligibility on a future date.

Why would I need my age in hours, minutes, and seconds?

Tap to view the answer

The precise breakdown is helpful for legal documents that require an exact age at a specific time, for medical records, actuarial calculations, or simply for personal curiosity. Activating the time option gives you granularity down to the second.

Is the age shown my completed age or running age?

Tap to view the answer

The calculator shows your completed age — meaning the number of full years, months, and days that have already passed. For example, if you were born on January 15, 1990 and today is June 30, 2026, you have completed 36 years, 5 months, and 15 days of life. You are in your 37th year, but your completed age is 36.

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How to Use This Calculator

Enter Date of Birth

Input your birth date using the date picker.

Set Target Date

Choose the date you want to calculate age at (defaults to today).

Optional: Include Time

Toggle time input for precise age calculation.

Review Results

See your exact age in years, months, days, weeks, hours, minutes, and seconds.

Key Tips

✓
The calculator accounts for leap years and varying month lengths.
✓
You can calculate age for any past or future date up to the year 2099.
✓
Works globally with international date formats.
✓
Includes time calculation for precise age in hours, minutes, and seconds.
✓
Use the 'Next Birthday' feature to plan for upcoming milestones.

How Age Calculation Works

The Basics of Age Calculation

Your age is the elapsed time between your date of birth and a reference date (usually today). The calculation subtracts the birth date from the target date, producing a result in years, months, and days. Our tool uses the Gregorian calendar and respects real-world calendar rules — including varying month lengths and leap years — so you get a precise result every time.

How Leap Years Affect Your Age

A leap year adds an extra day (February 29) every 4 years, with an exception for century years not divisible by 400. For someone born near the end of February, leap years slightly shift the day count. The calculator automatically accounts for every leap year between your birth date and target date. If you were born on February 29 in a leap year, the calculator recognizes your birthday falls on February 28 or March 1 in non-leap years, depending on convention.

Why Include Time of Birth?

By default, the calculator assumes midnight for both dates. Toggling the time option lets you enter an exact hour and minute. This matters for legal age thresholds — such as turning 18 or 21 at a specific time of day — and for anyone who needs precision down to the minute or second. The tool will then display age in hours, minutes, and seconds alongside the standard breakdown.

Display Formats and When to Use Each

The 'Detailed' format shows years, months, days, hours, minutes, and seconds — useful for formal documentation or curiosity. 'Compact' trims the output to years, months, and days, which is what most people need day to day. 'Years Only' gives a simple number, handy for age-restricted services or quick eligibility checks. Choose the format that matches your purpose.

Formula & methodology

Formula used

Calendar age

years, then months, then days are taken in turn from the date difference

Age is counted the way people count it: whole years first, then whole months, then the days left over — borrowing from the previous month when the day of month has not yet been reached.

Total elapsed units

total days = (target − birth) ÷ 86,400,000 ms;  weeks = days ÷ 7

Absolute elapsed time, derived from the millisecond difference between the two dates.

Variable definitions

Symbol	Meaning	Unit
birth date	Date of birth. the starting date	date
target date	Target date. the date to measure age at; defaults to today	date

Step-by-step calculation

1. Enter the date of birth
Set a target date to find age at some other moment.
2. Include the time of day if you need it
Without it both dates are treated as midnight.

Limitations

Ages are computed on calendar dates (year, month, day) exactly as written, so the result does not depend on your time zone. If a birth time is included it is treated as local clock time at both moments, and a birth in a different time zone can shift the elapsed hours.
Months are of unequal length, so 'months' in the breakdown means calendar months, not a fixed number of days. When an anniversary day does not exist in a month (born on the 31st, or 29 February), it is taken on that month's last day: a 31 January birth reaches one month on 28 February, and a 29 February birthday is observed on 28 February in non-leap years. Some legal systems use 1 March instead.
Decimal age (Years Only) is the whole years plus the fraction of the way through the current year of age.
The target date cannot precede the birth date; the calculator reports this rather than returning a negative age.

Calculator inputs

Date Information

Your results

Methodology

Formula & methodology

Formula used

Calendar age

Total elapsed units

Variable definitions

Step-by-step calculation

Limitations

How do I calculate my exact age in years, months, and days?

Does the age calculator account for leap years?

Can I calculate how old I will be on a future date?

Why would I need my age in hours, minutes, and seconds?

Is the age shown my completed age or running age?

Related calculators

More everyday calculators

Calculator inputs

Date Information

Your results

Methodology

How to Use This Calculator

Example: Born January 15, 1990

Understanding Your Results

Key Tips

How Age Calculation Works

The Basics of Age Calculation

How Leap Years Affect Your Age

Why Include Time of Birth?

Display Formats and When to Use Each

Formula & methodology

Formula used

Calendar age

Total elapsed units

Variable definitions

Step-by-step calculation

Limitations

How to Use This Calculator

Example: Born January 15, 1990

Understanding Your Results

Key Tips

How Age Calculation Works

The Basics of Age Calculation

How Leap Years Affect Your Age

Why Include Time of Birth?

Display Formats and When to Use Each