DATE
CALCULATOR
A date represents a specific day, month, and year in the calendar system, used for tracking events, appointments, and historical records. Dates help in organizing schedules, financial planning, and legal documentation. They are crucial in calculating age, anniversaries, deadlines, and important milestones. Various formats exist, such as DD/MM/YYYY or MM/DD/YYYY, depending on the region. Use our date calculator to find past or future dates, durations, and important time differences!
Days Between Date
Start Date:
End Date:
Total Years
Total Months
Total Weeks
Total Days
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Business Days
Holidays
Weekends
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Add or Subtract (Years, Months, Weeks, Days) from a Date
Start Date:
Year Input
Months Input
Weeks Input
Days Input
Day
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Date
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How to use Date Calculator?
Option 1: Days Between Two Dates
Enter Start Date:
​Select a start date from the date picker.
Enter End Date:
​​Select an end date from the date picker.
Select Weekend Preferences:
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Check the box for "Include Saturday" if you want Saturdays to be counted as holidays.
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Check the box for "Include Sunday" if you want Sundays to be counted as holidays.
View Results:
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Total Days: Displays the number of days between the two dates.
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Total Years, Months, and Days: Shows the difference in years, months, and days.
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Total Weeks + Days: Displays the number of full weeks and remaining days.
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Holidays: The total number of fixed national holidays within the date range.
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Business Days: The total working days, excluding holidays and selected weekends.
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Weekend Days: The total number of Saturdays and Sundays.
Option 2: Add or Subtract from a Date
Select Base Date:
Choose a starting date.
Choose Add or Subtract:
Select "Add" or "Subtract" from the dropdown.
Enter Time Adjustments:
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Years: Enter the number of years to add or subtract.
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Months: Enter the number of months to add or subtract.
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Weeks: Enter the number of weeks to add or subtract.
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Days: Enter the number of days to add or subtract.
View Results:
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Result Day: Displays the weekday of the resulting date (e.g., Monday).
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Result Date: Shows the final date in "DD Month YYYY" format.
​How does the Date Calculator determine the number of days between two dates?
he Date Calculator finds the total number of days between two selected dates by following these steps:
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Convert the Dates to Timestamps:
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Each date is internally represented as the number of milliseconds since January 1, 1970 (Unix Epoch Time).
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The calculator converts both the start date and end date into their respective timestamps.
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Calculate the Difference in Milliseconds:
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The calculator subtracts the timestamp of the start date from the timestamp of the end date.
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This results in a difference measured in milliseconds.
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Convert Milliseconds to Days:
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Since 1 day = 86,400,000 milliseconds (1000 milliseconds × 60 seconds × 60 minutes × 24 hours), the total milliseconds difference is divided by this value.
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Return the Final Day Count:
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The result is rounded down to the nearest whole number to ensure accuracy.
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The output is displayed as the total number of days between the two dates.
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Example Calculation:
Start Date: March 1, 2024
End Date: March 15, 2024
Difference in milliseconds: 1,209,600,000 ms
Days Difference: 1,209,600,000 / 86,400,000 = 14 days
This method ensures that the date difference is always precise, even when handling leap years or different month lengths.
How are business days calculated, and why are weekends and holidays excluded?
Business days refer to the total working days within a selected period, excluding weekends and fixed holidays. The calculation follows these steps:
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Determine the Total Days:
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The calculator first finds the total number of days between the two selected dates (as explained in Question 1).
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Identify Weekends Based on User Selection:
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The user selects whether to include or exclude Saturdays and Sundays.
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The calculator loops through each date and checks its weekday value:
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Saturday = 6, Sunday = 0 in JavaScript’s getDay() function.
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If the user has chosen to exclude weekends, the total business days count is reduced accordingly.
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Check for Fixed National Holidays:
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The calculator maintains a predefined list of national holidays:
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26 January (Republic Day)
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15 August (Independence Day)
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2 October (Gandhi Jayanti)
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For every date in the range, the calculator checks whether it matches one of these holidays. If it does, it is counted as a holiday and subtracted from the business days.
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Compute the Business Days:
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The final business days count is obtained by subtracting weekends and fixed holidays from the total number of days.
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Example Calculation (March 1, 2024 – March 31, 2024)
Total Days: 31
Weekends (Saturday + Sunday): 9
Fixed Holidays (if any fall in this range): 1 (Example: If March 26 was a holiday)
Business Days Calculation: 31 - 9 - 1 = 21 business days
This approach ensures that business days reflect an accurate count of working days, which is useful for payroll calculations, project deadlines, and work scheduling.
How does the calculator handle leap years and different month lengths?
Leap years and varying month lengths are handled automatically using JavaScript’s built-in Date Object. The key factors considered are:
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Leap Year Check:
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A leap year occurs if the year is divisible by 4, except when it is also divisible by 100 (unless it is also divisible by 400).
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Leap years have 366 days instead of 365, with February 29th as an extra day.
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Handling February’s Variable Length:
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The calculator checks if the selected date range includes February and determines whether the year is a leap year or a common year.
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If it’s a leap year, February is considered 29 days; otherwise, it is treated as 28 days.
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Different Month Lengths:
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The months April, June, September, and November have 30 days, while other months have 31 days (except February).
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The calculator accounts for these differences when calculating total months and days.
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Example:
From February 28, 2024, to March 1, 2024:
Since 2024 is a leap year, February has 29 days.
The total days difference is 2 days (Feb 29 and Mar 1).
From February 28, 2023, to March 1, 2023:
Since 2023 is NOT a leap year, February has 28 days.
The total days difference is 1 day.
By using JavaScript’s setDate() and getDate(), the calculator seamlessly adjusts for these variations.
How does the "Add/Subtract Date" feature work?
The Add/Subtract Date feature allows users to select a base date and add or subtract a certain number of years, months, weeks, or days.
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User Input:
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The user selects a base date (e.g., March 15, 2024).
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They enter values for years, months, weeks, and days.
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They choose “Add” or “Subtract” from a dropdown.
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Calculation Process:
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The calculator first converts weeks into days (weeks × 7).
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If the user chooses “Add”, the values are added to the base date.
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If the user chooses “Subtract”, the values are subtracted.
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Handling Month Overflows:
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If a user adds 1 month to January 31, it automatically adjusts to February 29 (in leap years) or February 28 (in common years).
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If subtracting months results in an invalid date (e.g., from March 31 to February), the calculator adjusts accordingly.
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Displaying Results:
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The day of the week (e.g., Monday, Tuesday) is displayed.
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The formatted date is shown (e.g., 15 March 2025).
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Example Calculation (March 15, 2024 + 2 months, 10 days)
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New Date: May 25, 2024
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Day of the Week: Saturday
This ensures users can accurately adjust dates for scheduling, forecasting, and planning purposes.
How does the calculator determine total years, months, weeks, and days?
The calculator splits the total days difference into years, months, weeks, and days by following these steps:
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Years Calculation:
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It calculates how many full years fit within the total days.
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If the month or day does not complete a full year, it remains in the months/days calculation.
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Months Calculation:
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It calculates how many full months fit within the remaining days after counting full years.
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Since months have different lengths, the calculation considers actual month days.
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Weeks and Days Calculation:
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The remaining days are divided into full weeks and extra days.
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Example Calculation (March 14, 2024 – March 14, 2025)
Total Days: 365
Total Years: 1 year
Total Months: 12 months
Total Weeks: 52 weeks + 1 day
This provides an easy-to-understand breakdown for various time intervals.
Can the calculator be used for work schedules and project deadlines?
Yes, the Date Calculator is widely useful for:
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Project planning (business days help set realistic deadlines).
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Employee leave tracking (excluding weekends/holidays).
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Event scheduling (determining the number of weeks before an event).
By incorporating business days, weekends, and holidays, the calculator provides accurate results for real-world scheduling needs.
Use the Date Calculator to find days, add or subtract dates, and count business days easily!