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Age Calculator

Private: nothing leaves your browser

Exact to the day
  • Exact age - -
  • Next birthday - -
  • In months -
  • In weeks -
  • In days -
  • In hours -

Your exact age in years, months and days, plus the same span counted in months, weeks, days and hours, and how long there is until the next birthday. Set the second date to work out an age on any day, past or future.

About this age calculator

Counting an age sounds trivial and is not, because months are not the same length. Subtracting the dates and dividing by 30 gives an answer that drifts by days, and subtracting the day numbers directly can give you a negative remainder. This settles the whole months first and then counts the real days left over, so the days figure is always a true day count and never negative.

Everything is worked out on local calendar dates rather than timestamps, which is what keeps the result steady across timezones and daylight saving changes. The second box lets you set any reference date, so you can check an age on a joining date, an exam cut off or a date years from now. If the question is the gap between two dates rather than somebody's age, the date difference calculator counts it both ways and separates the weekdays.

How to calculate your exact age

  1. Pick the date of birth. You can type it as well as use the calendar.
  2. Leave Age as on at today, or change it to work out the age on any other date.
  3. Read the exact age, then the same span counted in months, weeks, days and hours.
  4. The next birthday panel shows the date, the day count and the age being turned.
  5. Press Copy for all of it as plain text, ready to paste into a form or a message.

Common questions about calculating age

How is the age worked out exactly?
By counting complete years first, then complete months, then the days that are left. The leftover days are measured from the last monthly anniversary to the reference date, so they are real days and always between 0 and 30. This is the same method a passport office or a school admission form uses, and it never divides by an average month length.

What happens with a 29 February birthday?
In a common year the birthday is taken as 28 February, which is the last day of the month the birthday belongs to. That is the same clamping used for month arithmetic everywhere in this calculator, so the age steps up on the 28th in a common year and on the 29th in a leap year. Some jurisdictions use 1 March instead, so check if a legal date matters.

Why is 31 January plus one month not 3 March?
Because a month later than the 31st has to land in a month that has no 31st, so it is clamped to the last day: 28 or 29 February. Adding 31 days instead would overshoot into March, which is the bug behind most wrong age and due date calculations. This tool clamps rather than overshoots.

Can I work out an age on a future date?
Yes. Set Age as on to any date after the date of birth, including one years ahead, and the full breakdown is worked out for that day. The only combination with no answer is a date of birth later than the reference date, and that is said plainly instead of showing a negative age.

Is my date of birth stored?
No. The calculation is JavaScript running on this page, so the date stays on your own device. Nothing is uploaded, logged or saved, and the page keeps working with your connection switched off. Today's date also comes from your own device rather than a server.

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