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Calculate the difference between two dates or add/subtract time from a date. Get results in years, months, weeks, and days with business day calculations.
Please select a start date
Start Date
This calculator provides accurate date calculations based on the Gregorian calendar. Business day calculations exclude weekends (Saturday and Sunday) but do not account for holidays.
Business days are calculated as Monday through Friday. For precise business day calculations including regional holidays, consult a holiday-aware calendar system.
A date calculator is a versatile tool that performs date arithmetic and comparisons. It can calculate the exact difference between two dates (in years, months, weeks, and days) or add/subtract time periods from a specific date to find a future or past date.
The calculator uses the Gregorian calendar system with algorithms that account for varying month lengths (28-31 days) and leap years. When finding the difference between dates, it calculates the total elapsed time and breaks it down into years, months, and days.
Find the exact time span between two dates in years, months, days, and weeks
Add or subtract any combination of years, months, weeks, and days
Automatically handles leap years and varying month lengths
View results in multiple formats (breakdown or totals)
Adding months to January 31 adjusts to last day of target month (Feb 28/29)
Leap years: divisible by 4, except centuries unless divisible by 400
Gregorian calendar dates work best from October 1582 onwards
Use include end date option for inclusive counting
This calculator is completely accurate for all dates in the Gregorian calendar (1582 onwards). It correctly handles leap years, varying month lengths, and all calendar edge cases.
When you add months to a date like January 31, the calculator adjusts to the last valid day of the target month. January 31 + 1 month = February 28 (or 29 in a leap year).
Leap years occur every 4 years (except centuries unless divisible by 400). February has 29 days in leap years. The calculator automatically accounts for this.
Yes, the calculator works for any date from October 1582 (Gregorian calendar adoption) through the foreseeable future.
Total days is the complete count (e.g., 400 days). The breakdown expresses the same period as years, months, and days (e.g., 1 year, 1 month, 5 days).
Use 'Find Date Difference' mode with their birth date as start and today as end. For more detail including zodiac signs, use our Age Calculator.
You can choose with the 'Include end date in count' option. Enable it to count both start and end dates, disable for exclusive counting.
Select 'Add/Subtract Time' mode, choose 'Subtract', enter the years, months, weeks, or days to subtract, and the calculator shows the resulting date.