Practical guide 3 min read
How to count business days between two dates
Count working days with the right weekends, public holidays and days off, and avoid the classic off-by-one mistake.
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Utility
Age Calculator
Calculate age on any date in complete years, months and days, plus total days lived.
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Choose your options to begin.
Excluded holidays and custom dates
How this calculation works
Age uses complete calendar months, split into years and months, followed by remaining days. Month-end dates clamp to the last valid day. Future birth dates are rejected.
Worked examples
- Someone born on May 17, 1990 is 36 years, 4 months and 13 days old on September 30, 2026: 13,285 days in all.
- Someone born on February 29, 2000 turns 25 on February 28, 2025, and is 24 years, 11 months and 29 days old the day before.
Questions
How is age calculated?
In complete calendar months from the date of birth, shown as years and months, then the days left over. That's how age is usually stated, so you're a year older on your birthday itself.
When does someone born on February 29 have a birthday?
In years without a February 29, this calculator counts the birthday on February 28, the last day of February. Some laws use March 1 instead, so check which applies when a legal age matters.
Can I find an age on a past or future date?
Yes. Set “Age on date” to any date on or after the date of birth, such as a school cutoff date or the day of a trip.
Part of Date Calculator
Calculate date differences, business days, age, date offsets and work hours with custom workweeks, holiday calendars and CSV exports.
A little guidance