Age Calculator
Enter a date of birth to get exact age in years, months and days — as of today or any date — plus totals in weeks, days, hours, minutes and seconds, all in your browser.
The Age Calculator runs entirely in your browser. The dates you enter never leave your device and nothing is uploaded to ArrayKit.
Open the Date Duration Calculator
About Age Calculator
The Age Calculator turns a date of birth into an exact age you can act on. Enter the birth date and it reports the precise gap in years, months and days using standard calendar borrowing, then restates that same age as total months, weeks, days, hours, minutes and seconds. By default it measures the age as of today, but the second field — Age at the date of — accepts any past or future date, so you can find how old someone was on a given day, how old they will be on a milestone, or the age between two dates. Optional time-of-day inputs sharpen the hours, minutes and seconds. Because it uses real month lengths and leap years, a February 29 birthday is handled correctly, and the next-birthday countdown folds to February 28 in ordinary years. The whole calculation runs on your device; the dates you enter are never uploaded.
Features
- Exact age in years, months and days from any date of birth
- Age as of today or any past or future reference date
- Same age restated in total months, weeks, days, hours, minutes and seconds
- Optional time-of-day inputs for precise hours, minutes and seconds
- Countdown of days until the next birthday, with the age you will turn
- Leap-year aware: February 29 birthdays resolve to a real date every year
- Copy the exact-age line or the next-birthday date in one click
- Runs entirely in your browser with nothing sent anywhere
How to use the Age Calculator
- Pick or type a date of birth in the first field
- Leave the second field on today, or set any target date to measure age at
- Optionally add a time of day to either field for finer totals
- Read the exact age in years, months and days at the top
- Check the totals in months, weeks, days, hours, minutes and seconds
Example
Input
Date of birth: 1990-06-15
Age at the date of: 2020-06-20
Output
Exact age: 30 years, 0 months, 5 days
Or: 360 months · 1,567 weeks · 10,968 days
Next birthday: 2021-06-15 (360 days, turning 31)
Age is measured with real calendar months, not fixed 30-day blocks.
Common errors & troubleshooting
- The result shows one fewer year than expected. — Age only counts a full year once the birthday has actually passed. Before the birthday in the reference year you are still the previous age, which is why the years value drops by one until the day arrives.
- A February 29 birthday shows an odd next-birthday date. — In non-leap years there is no February 29, so the countdown uses February 28. On the next leap year the birthday lands back on the 29th.
- Nothing is calculated after entering the dates. — Make sure both are real calendar days in YYYY-MM-DD form and that the date of birth is on or before the target date — a birth date after the target is rejected.
- Total days looks slightly off from a year-times-365 estimate. — The total counts real days including every leap day in the span, so a range covering leap years will be a little larger than 365 per year.
Frequently asked questions
- How does the Age Calculator compute exact years, months and days?
- It subtracts the birth date from the reference date field by field, borrowing days from the previous month and months from the year when a value would go negative. That gives a clean breakdown like '30 years, 2 months, 4 days' using real month lengths rather than fixed 30-day months.
- Can I calculate age as of a specific date, not just today?
- Yes. The second field, Age at the date of, defaults to today but accepts any past or future date. Set it to measure how old someone was on a given day, how old they will be on a future milestone, or the age between two dates.
- How is a February 29 birthday handled?
- Leap-day birthdays are tracked as February 29. For the next-birthday countdown in a year that is not a leap year, the tool uses February 28, and in leap years it uses February 29, so there is always a concrete date to count toward.
- What do the total months, weeks, days, hours and seconds mean?
- They restate the same age in a single unit instead of a years-months-days breakdown: total months is years times twelve plus extra months, and total weeks, days, hours, minutes and seconds count the real elapsed time, including every leap day, from birth to the reference date.
- Why does the age not increase until the birthday?
- A full year is only counted once the anniversary of the birth date has passed. Until that birthday arrives in the reference year, the years value stays at the previous number and the months and days fill in the remainder.
- Does my date of birth get uploaded anywhere?
- No. The Age Calculator runs entirely in your browser. The dates you enter are used only on your device to do the math and are never sent to ArrayKit or any server.
Related tools
- Date Duration Calculator — Calculate the duration between two dates in years, months, weeks, days and business days.
- Date Calculator — Add or subtract years, months, weeks and days from a date to find the resulting date.
- Business Days Calculator — Add or subtract working days from a date, or count business days between two dates.
- Duration Converter — Convert a duration between seconds, minutes, hours, days, HH:MM:SS and human formats.
- Unix Timestamp Converter — Convert between Unix timestamps and human dates (local + UTC).
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