What these tools do
The date difference calculator counts the days, weeks, months and business days between any two dates, with an option to include the final day. The age calculator turns a date of birth into an exact age in years, months and days, plus totals in weeks and days and a countdown to the next birthday.
The inclusive question
Most date disputes come down to one thing: does the last day count? A 30-day notice period, a hotel stay and a free trial can each use a different convention. Both tools let you switch between counting the gap between dates and counting both endpoints, so you can match whatever your contract or booking says.
Business days and holidays
Business days here mean Monday through Friday. Public holidays are not removed, because they differ by country, state and employer. In the United States there are eleven federal holidays, and several move each year because they fall on a given weekday rather than a fixed date. Start with the weekday count and subtract the holidays that apply to your calendar.
Leap years and calendar quirks
Leap years are handled automatically: a year is a leap year when it is divisible by 4, except century years that are not divisible by 400. Months are trickier, because they range from 28 to 31 days, so "one month" is a calendar step rather than a fixed number of days. Where that distinction changes the result, the page explains which convention it used.
Privacy
Dates you enter, including birth dates, stay in your browser. Nothing is sent to a server, and closing the page clears it.
Last reviewed on by the Dailycaltor team.