Calculate days between dates, add or subtract days from a date, and determine weekdays vs weekends.
A days calculator helps you perform various date-related calculations, including calculating the number of days between two dates, adding or subtracting days from a date, and analyzing weekdays versus weekends.
From January 1, 2023 to January 31, 2023:
Total days: 30 days
Weekdays: 21 days (assuming no holidays)
Weekends: 8 days
Date calculations are essential for various purposes:
• Days between dates: Difference in milliseconds converted to days
• Adding days to date: Base date + (days × milliseconds per day)
• Weekday calculation: Using modulo 7 operations on Julian day numbers
• Leap year detection: Year divisible by 4 but not by 100, unless also divisible by 400
Understanding these calculations can help you better plan projects, manage schedules, and meet important deadlines.
| Month | Days | Leap Year |
|---|---|---|
| January | 31 | 31 |
| February | 28 | 29 |
| March | 31 | 31 |
| April | 30 | 30 |
| May | 31 | 31 |
| June | 30 | 30 |
| July | 31 | 31 |
| August | 31 | 31 |
| September | 30 | 30 |
| October | 31 | 31 |
| November | 30 | 30 |
| December | 31 | 31 |
• New Year's Day: January 1
• Memorial Day: Last Monday in May
• Independence Day: July 4
• Labor Day: First Monday in September
• Thanksgiving: Fourth Thursday in November
• Christmas Day: December 25
In any 400-year cycle:
• Each weekday occurs 56-58 times each month
• February has 28-29 weekdays in non-leap years
• 31-day months have 22-23 weekdays
• 30-day months have 20-21 weekdays