Age Calculator
Exact age in years, months, and days from a birth date. e.g. “How old is someone born on 12 May 1990?”
Enter your values
Results update as you type. All calculation happens in your browser.
Methodology
Exact age in years, months, and days from a birth date. This tool uses a standard, documented formula and runs entirely on your device.
Last reviewed January 2026 · Runs client-side
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Calculating an exact age between two dates
An exact age is more than a count of years, it's years, months, and days, and getting it right means accounting for months of different lengths and leap years. This calculator does that arithmetic precisely between any two dates.
It's useful well beyond birthdays: eligibility cut-offs, anniversaries, and record-keeping all depend on an accurate elapsed time between a start date and a reference date.
How to use this calculator
- Enter the date of birth.
- Set the date to calculate the age at, it defaults to today.
- Read the age in years, months, and days, plus the countdown to the next birthday.
What the inputs mean
- Date of birth
- The starting date.
- Calculate age at
- Any reference date; leave it as today for a current age.
Someone born on 12 May 1990 is, as of mid-2026, 36 years old, the tool also shows the exact months and days and how far off the next birthday is.
The formula, in plain terms
The age is the elapsed years, months, and days between the two dates, adjusting for month lengths and leap years.
Good to know
- Set the second date to a future deadline to check whether an age requirement will be met by then.
- Total-days figures are handy for precise record-keeping.
Frequently asked questions
Does it handle leap years?
Yes. Day counts and the months/days breakdown account for leap years and varying month lengths.
Last reviewed January 2026. This explainer is general information, not professional advice.