How to use the last day of month calculator
- Choose the month from the list.
- Enter the year, from 1 to 9999.
- Read the last day of the month, the weekday it falls on, the number of days and whether the year is a leap year.
- Use the table to see the last day of every month in that year.
Formula
31 days: January, March, May, July, August, October, December
30 days: April, June, September, November
February: 29 days in a leap year, 28 otherwise
Leap year: divisible by 4, except years divisible by 100 unless they are also divisible by 400
The weekday comes from counting whole days on the Gregorian calendar, so it does not depend on your time zone.
February 2024 and February 2023
2024 is divisible by 4 and not by 100, so it is a leap year and February ends on the 29th, which is a Thursday. 2023 is not a leap year, so February ends on the 28th, a Tuesday.
The year 1900 is divisible by 100 but not by 400, so it is not a leap year, while 2000 is divisible by 400 and is one. The table for 2024 lists every month end, from Wednesday, January 31 to Tuesday, December 31.
Why month lengths vary
Month lengths come from the Gregorian calendar, which adds a leap day to keep the calendar in step with the seasons. Most years divisible by 4 are leap years, and the rule about centuries removes three leap years every 400 years.
The rhyme about thirty days hath September is a way many people remember which months are shorter. The table in the result gives you the full list for any year.
Calendar month ends versus business month ends
The last day of a month is not always a business day. Payroll, billing and fiscal reporting may use a different day, such as the last business day, a set cutoff or a 4-4-5 calendar. This tool gives the calendar month end only.
To see the weekday of any date use the day of week calculator. For adding months to a date try the date calculator, and for counting days use the days between dates calculator.
Assumptions and limits
- The Gregorian calendar is applied to every year entered, including years before it was adopted in some places.
- The year is a whole number from 1 to 9999.
- The result is the calendar month end, not a fiscal or payroll cutoff.
- Weekdays are counted from whole days and do not depend on time zones.
Frequently asked questions
What is the last day of February?
It is the 28th in most years and the 29th in a leap year. For example, February 2024 ends on the 29th and February 2023 on the 28th.
How do I know if a year is a leap year?
A year divisible by 4 is a leap year, except that years divisible by 100 are leap years only when they are also divisible by 400. So 2000 was a leap year and 1900 was not.
Which months have 31 days?
January, March, May, July, August, October and December. April, June, September and November have 30 days, and February has 28 or 29.
Does the tool give the last business day?
No. It gives the calendar month end and the weekday it falls on. If the date is a weekend, check your own rule for the business day you need.