Date Calculator
Calculate date differences, add or subtract days, weeks, months, and years from any date
Choose Calculation Mode
Date Difference
Quick Presets
Calculation Results
Total Days
Working Days
Detailed Breakdown
Result Date
How we calculated this
What if?
Each row recalculates with your current inputs. Tap a row to apply it.
Select dates to calculate
Choose your calculation mode and enter the required dates
How to Use the Date Calculator
Professional date calculations made simple
Choose Mode
Select from date difference, add time, or subtract time calculations
Enter Dates
Input your dates using the convenient date picker interface
Get Results
View detailed breakdowns including working days and time periods
Calendar calculation rules
Elapsed days exclude the start date. The separate weekday count includes both endpoints and excludes Saturdays and Sundays; public holidays are not deducted. Dates are Gregorian calendar dates, independent of the device timezone. Month and year additions clamp to the last valid day of the target month. For a Canadian booking, use an unambiguous ISO date such as 2026-10-11 when exchanging data between English and French systems. October 11 to October 12 is 1 elapsed day. The Monday–Friday count does not subtract federal or provincial holidays.
Authoritative sources and references
The official standards, guidelines, and research behind this calculator's methodology.
Date Calculator FAQ
How are elapsed days and weekdays counted?
Elapsed days exclude the starting date: the same date gives 0 days and January 1 to January 2 gives 1 day. The separate Monday–Friday count includes both endpoints and does not deduct public holidays.
How do I add weeks or months?
Choose Add or Subtract and enter days, months or years. There is no separate weeks field: enter 7 days for one week. Month and year additions clamp to the last valid day of the target month.
What happens at month ends and leap days?
January 31, 2026 plus one month gives February 28, 2026. February 29, 2024 plus one year gives February 28, 2025. These are this calculator’s chosen calendar arithmetic rules.
Does a calendar day always mean 24 elapsed hours?
This tool compares Gregorian calendar dates, not instants or timestamps. A local day across a daylight saving transition can span 23 or 25 elapsed hours. Use a timestamp difference tool for an elapsed time interval. For a Canadian booking, use an unambiguous ISO date such as 2026-10-11 when exchanging data between English and French systems. October 11 to October 12 is 1 elapsed day. The Monday–Friday count does not subtract federal or provincial holidays.