🎂

Age Calculator

Calculate exact age in years, months, and days

Math Finance
Loading tool...

How to Use Age Calculator

What is an Age Calculator?

An age calculator is a tool that computes the exact duration between two dates, typically from your date of birth to the current date (or any reference date you choose). It provides your age in multiple units: years, months, weeks, days, hours, and even minutes.

This tool uses precise calendar arithmetic, accounting for leap years, varying month lengths, and time zones to give you accurate results every time.

Why Use an Age Calculator?

While you know your age in years, an age calculator provides insights you might not have considered:

  • Exact age breakdown: Years, months, and days (not just "I'm 25")
  • Fun statistics: How many days, hours, or minutes you've lived
  • Next birthday countdown: Days remaining until your next birthday
  • Day of birth: What day of the week you were born on
  • Age verification: Quick calculation for forms, applications, or legal purposes
  • Age difference: Calculate age as of any date (past or future)

How to Use This Tool

Step 1: Enter Your Date of Birth

  1. Click the Date of birth field
  2. Use the date picker to select your birth date
  3. Or type the date in YYYY-MM-DD format (e.g., 1990-05-15)

Note: The date must be a valid calendar date in the past.

Step 2: Choose the "As Of" Date

The "As of" date is the reference point for calculating your age. By default, this is today's date.

Options:

  • Leave it as today to find your current age
  • Change it to a past date to find your age on a specific day
  • Change it to a future date to find your age on an upcoming date

Quick tip: Click "Use today" to reset the "As of" date to the current date.

Step 3: Calculate Your Age

Click the Calculate age button to compute your exact age.

Step 4: Review Your Results

The calculator displays:

  1. Age summary: Your age in years, months, and days (e.g., "25 years, 3 months, and 12 days")
  2. Day of birth: The day of the week you were born
  3. Total months: Total months you've lived
  4. Weeks & days: Total weeks plus remaining days
  5. Total days: Total days since birth
  6. Total hours: Approximate hours (days × 24)
  7. Total minutes: Approximate minutes (hours × 60)
  8. Next birthday: The date of your next birthday and how many days until then

Common Use Cases

Calculate Your Current Age

Scenario: You want to know your exact age in years, months, and days.

  1. Enter your Date of birth
  2. Leave As of date as today (default)
  3. Click Calculate age

Result: Your current age breakdown with fun stats like total days lived and days until your next birthday.

Find Your Age on a Past Date

Scenario: You want to know how old you were on a specific historical date (e.g., graduation day, wedding day).

  1. Enter your Date of birth
  2. Change As of date to the past date (e.g., 2015-06-20)
  3. Click Calculate age

Result: Your age as it was on that specific date.

Calculate Future Age

Scenario: You want to know how old you'll be on a future date (e.g., retirement, milestone birthday).

  1. Enter your Date of birth
  2. Change As of date to the future date (e.g., 2030-01-01)
  3. Click Calculate age

Result: Your age as it will be on that future date.

Days Until Next Birthday

Scenario: You want to know how many days until your next birthday.

  1. Enter your Date of birth
  2. Leave As of date as today
  3. Click Calculate age
  4. Look at the Next birthday card

Result: The exact date of your next birthday and the countdown in days.

What Day Was I Born On?

Scenario: You want to know what day of the week you were born.

  1. Enter your Date of birth
  2. Leave As of date as today (or any date)
  3. Click Calculate age
  4. Look at the Age summary section

Result: "You were born on [Day of Week]" (e.g., "You were born on Monday").

Age for Legal/Form Purposes

Scenario: You need to calculate your age for a form, application, or legal document.

  1. Enter your Date of birth
  2. Set As of date to the effective date of the form (or leave as today)
  3. Click Calculate age

Result: Exact age in years, months, and days for accurate form completion.

Calculate Someone Else's Age

Scenario: You want to calculate the age of a family member, friend, or historical figure.

  1. Enter their Date of birth
  2. Set As of date to today (or any reference date)
  3. Click Calculate age

Result: Their exact age as of the chosen date.

Understanding the Results

Years, Months, and Days

This is your calendar age—the most intuitive breakdown.

Example: If you were born on January 15, 2000, and today is April 27, 2025:

  • Years: 25 (you've lived through 25 full years)
  • Months: 3 (3 additional months since your last birthday)
  • Days: 12 (12 additional days since the start of April)

Result: "25 years, 3 months, and 12 days"

Total Months

The cumulative number of months since birth, including partial months.

Formula: (Years × 12) + Months

Example: 25 years, 3 months = (25 × 12) + 3 = 303 months

Weeks & Days

The total number of complete weeks since birth, plus remaining days.

Example: If you've lived 9,263 days:

  • Weeks: 1,323 weeks (9,263 ÷ 7 = 1,323 remainder 2)
  • Remaining days: 2

Result: "1,323 weeks + 2 additional days"

Total Days

The total number of days since your birth date, calculated precisely.

Note: This accounts for leap years and varying month lengths.

Example: 9,263 days

Total Hours

An approximation based on total days × 24.

Example: 9,263 days × 24 = 222,312 hours

Caveat: This assumes exactly 24 hours per day and doesn't account for daylight saving time adjustments.

Total Minutes

An approximation based on total hours × 60.

Example: 222,312 hours × 60 = 13,338,720 minutes

Purpose: Just for fun—it's impressive to see how many minutes you've lived!

Day of Birth

The day of the week you were born (e.g., Monday, Tuesday).

Example: "You were born on Friday."

Fun fact: Some cultures believe the day of the week you're born influences your personality!

Next Birthday

The date of your upcoming birthday and how many days remain.

Calculation:

  • If your birthday hasn't occurred this year, next birthday = this year's birthday
  • If your birthday has already passed, next birthday = next year's birthday

Example: If today is April 27, 2025, and your birthday is January 15:

  • Next birthday: January 15, 2026
  • Days remaining: 263 days

How Age Calculation Works

Calendar Age (Years, Months, Days)

The calculator uses calendar arithmetic to compute your age:

  1. Years: Difference in years between birth year and "as of" year
  2. Months: Difference in months, adjusted if "as of" day is earlier in the month
  3. Days: Difference in days, adjusted for month-end variations

Example: Born January 15, 2000 → As of April 27, 2025

  • Years: 2025 - 2000 = 25
  • Months: April (4) - January (1) = 3
  • Days: 27 - 15 = 12

Result: 25 years, 3 months, 12 days

Leap Years

Leap years have 366 days instead of 365. The calculator automatically accounts for leap years when calculating total days.

Leap year rules:

  • Divisible by 4 → Leap year
  • Divisible by 100 → Not a leap year (exception below)
  • Divisible by 400 → Leap year

Examples: 2000 (leap), 2024 (leap), 1900 (not leap), 2100 (not leap)

Time Zone Normalization

All dates are normalized to local midnight (00:00:00) to avoid time zone edge cases. This ensures consistent results regardless of the time of day you use the calculator.

Tips and Best Practices

Use Today's Date as Default

The "As of" date defaults to today for convenience. If you accidentally change it, click "Use today" to reset.

Calculate Age for Special Dates

Use this tool to calculate:

  • Age on your wedding anniversary
  • Age when you graduated
  • Age on historical events (e.g., "How old was I when the iPhone launched?")

Bookmark for Quick Access

Bookmark this page to quickly calculate ages for forms, applications, or curiosity.

Share with Friends

Share this tool with friends to calculate their ages or plan birthday countdowns together.

Privacy Note

All calculations happen locally in your browser. No dates or personal information are sent to any server or stored anywhere.

Common Questions

Why Does My Age Seem Different Than Expected?

The calculator uses exact calendar arithmetic, which includes months and days. If you typically round your age (e.g., "I'm 25" when you're actually 25 years, 3 months, and 12 days), the detailed breakdown might seem more specific.

Does This Account for Leap Years?

Yes. The calculator uses JavaScript's native Date object, which automatically handles leap years, daylight saving time transitions, and month-end variations.

Can I Calculate Someone's Age Who Hasn't Been Born Yet?

Technically, yes—if you enter a future date of birth and a later "as of" date, the calculator will compute the difference. However, this scenario isn't typical and may not be meaningful.

What If I Enter an Invalid Date?

The calculator validates both dates and displays an error message if:

  • The date is invalid (e.g., February 30)
  • The date of birth is in the future
  • The date of birth is after the "as of" date

How Accurate Is the "Total Hours" and "Total Minutes" Calculation?

These are approximations based on total days × 24 hours × 60 minutes. They don't account for:

  • Daylight saving time adjustments
  • Leap seconds
  • Time zone changes

For most purposes, the approximation is sufficiently accurate.

Troubleshooting

"Please enter a valid date of birth"

Problem: The date of birth field is empty or contains an invalid date.

Solution: Click the date picker and select a valid date, or type a date in YYYY-MM-DD format (e.g., 1990-05-15).

"Date of birth must be before the 'as of' date"

Problem: The date of birth is later than the "as of" date.

Solution: Ensure the date of birth is before the "as of" date. For example:

  • Date of birth: 1990-05-15
  • As of: 2025-04-27 (later than DOB ✅)

No Results Displayed

Problem: You entered dates but don't see results.

Solution: Click the Calculate age button to compute and display the results.

Wrong Day of Birth Displayed

Problem: The day of the week seems incorrect.

Solution: Double-check the date of birth. JavaScript's Date object is accurate for all dates in the Gregorian calendar (post-1582). If you're calculating for very old dates (e.g., before 1582), historical calendar differences may apply.

Performance and Privacy

Browser-Based Calculation

This tool runs 100% in your browser:

  • ✅ No data sent to servers
  • ✅ Works offline (once loaded)
  • ✅ No cookies or tracking
  • ✅ Instant results (no network latency)

Compatibility

Supported browsers:

  • Chrome 66+ (2018)
  • Firefox 63+ (2018)
  • Safari 13.1+ (2020)
  • Edge 79+ (2020)

All modern browsers with native Date support work perfectly.

Fun Facts About Ages

Life Milestones in Days

  • 1,000 days old: ~2 years, 9 months
  • 5,000 days old: ~13 years, 8 months
  • 10,000 days old: ~27 years, 4 months
  • 18,250 days old: ~50 years (celebrate your 50th birthday!)
  • 25,000 days old: ~68 years, 5 months

Average Human Lifespan

  • Global average: ~73 years = ~26,645 days
  • Developed countries: ~80 years = ~29,200 days

Famous Ages

  • Legal adulthood (USA): 18 years = ~6,570 days
  • Retirement age (USA): 65 years = ~23,725 days
  • Centenarian: 100 years = ~36,500 days

External Resources

Frequently Asked Questions

Share Your Feedback

Help us improve this tool by sharing your experience

We will only use this to follow up on your feedback