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Date Calculator

Calculate the number of days between two dates, add or subtract days from a date, and find date differences.

Date Calculation

Date Results

Result: 7 days
Days: 7
Weeks: 1
Weekdays: 5
Business Days: 5

About Date Calculations

Date calculations are essential for planning events, tracking project timelines, calculating ages, and many other applications. This calculator helps you determine the number of days between two dates or find a date by adding or subtracting days from a given date.

Example Calculation:

If you want to know how many days are between January 1, 2023 and January 8, 2023:

The result would be 7 days, which is 1 week and 0 months.

If you add 7 days to January 1, 2023, the result would be January 8, 2023.

Date calculations consider the varying lengths of months and leap years. February has 28 days in common years and 29 days in leap years. The other months have either 30 or 31 days.

Business Days vs Calendar Days

• Calendar Days: Include all days of the week (Monday through Sunday)

• Business Days: Typically Monday through Friday, excluding weekends

• Weekdays: Monday through Friday

• Weekend Days: Saturday and Sunday

When calculating business days, keep in mind that holidays may affect the count, though this calculator doesn't account for specific holidays.

Date Calculation Methods

The calculation of days between dates is based on the Gregorian calendar, which is the most widely used civil calendar today.

Days = (End Date - Start Date) / (24 × 60 × 60 × 1000)

When adding or subtracting days:

New Date = Base Date ± (Days × 24 × 60 × 60 × 1000)

Leap Year Rules

A year is a leap year if it is:

• Divisible by 4, but not divisible by 100, unless

• Also divisible by 400

This means 2000 was a leap year, but 1900 was not.

Common Date Calculations

• Project planning and deadlines

• Age calculation

• Interest calculations for finance

• Rental periods and billing cycles

• Event planning