Date Calculator

Count days between two dates, or add and subtract days, weeks, months, and years.

Smart Tips

• Days between counts midnights crossed. January 1 to January 2 is 1 day.

• February 29, 2024 plus one day is March 1, 2024.

• January 31 plus one month lands on the last day of February.

• February 29 plus one year lands on February 28 in a common year.

• 1900 is not a leap year. 2000 is a leap year.

• Age from a birth date is a different calculator.

The Formula

days = serial(end) − serial(start); months clamp the day

serialA whole-day count on the Gregorian calendar.

leapYear divisible by 4, except centuries not divisible by 400.

clampJanuary 31 plus 1 month becomes February 28 or 29.

weekSeven days, including a leap day if the week contains one.

The count does not include both endpoints. Adding a month or a year keeps the day number when that day exists.

Key Insights

Leap day

February 28, 2024 to March 1, 2024 is 2 days because February 29 is in the span.

Century rule

1900 has 28 days in February. 2000 has 29.

End of month

March 31 minus one month is February 29 in 2024 and February 28 in 2023.

Not age

This page does not turn a birth date into years, months, and days of age.

Frequently Asked Questions

No. The result is the number of midnights between the two dates. The same date is 0. The next day is 1. February 28, 2024 to March 1, 2024 is 2 because 2024 has a February 29.

The month number moves, and the day stays when that day exists. January 31 plus one month is February 29 in a leap year and February 28 otherwise. March 31 minus one month uses the same rule.

It becomes February 28 of the next year when that year is not a leap year. February 29, 2024 plus one year is February 28, 2025.

A year divisible by 100 is a leap year only when it is also divisible by 400. 1900 is not a leap year, so February 28, 1900 plus one day is March 1, 1900. 2000 is a leap year.

No. Age from a birth date to an as-of date is the age calculator. This page counts a span or moves a date by days, weeks, months, or years.

Month lengths follow the Gregorian calendar. A year divisible by 4 is a leap year, except a century year that is not divisible by 400. That is the rule published by the U.S. Naval Observatory. aa.usno.navy.mil/faq/leap_years

Responsive Ad Space

Result

Enter dates to calculate

Weeks and days

Start

End

Note:Months and years keep the day when it exists and otherwise use the last day of the month. February 29 plus one year is February 28. Leap years follow the Gregorian rule.