Dates & Time

Age in Decimal Years

Turns a date of birth into a precise decimal age, like 25.34 years. It also gives total days, weeks, hours, minutes, and seconds lived, plus the years-months-days breakdown.

How to use
  1. Enter the date of birth.
  2. Set a reference date, or leave it on today.
As of
Decimal age
—

years, to two decimals

Calendar Y / M / D
—
Total months
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Total weeks
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Total days
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Date math uses your inputs as given; check time-zone and leap-year edge cases.
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How it's calculated

age = whole years + (days since last birthday ÷ days in that year)

whole years = completed years from birth to the reference date, days in that year = 365 or 366 between the last and next birthday.

Common questions

What does a decimal age like 25.34 mean?

It is the whole age plus the fraction of the year completed since the last birthday, so 25.34 is a bit past a third of the way to age 26.

Can I find age on a past or future date?

Yes, set any reference date and the age is calculated as of that date instead of today.

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