Date Calculator
Calculate the exact difference between two dates in days, weeks, months, and years. Also shows business days and total hours.
Exact Difference
0 days
0
Days
0
Weeks
0
Months
0
Years
Hours
0
Minutes
0
Business Days
1
Weekends
-1
How Date Difference is Calculated
The calculator computes the absolute time between two dates using calendar math that correctly handles varying month lengths (28-31 days) and leap years.
Calculation Method
Days: End date − Start date (calendar days)
Weeks: Total days ÷ 7 (rounded down)
Months: Difference in (year×12 + month) values
Exact: Y years, M months, D days (like age calculation)
Business Days: Weekdays only (Mon–Fri), excluding weekends
Common Uses
- Calculate days until a deadline or event
- Find how many business days between two dates
- Determine the length of a project or contract
- Calculate days of pregnancy or treatment duration
- Plan vacation length or lease periods
Frequently Asked Questions
How does this calculator count days?
It counts the number of calendar days between two dates (exclusive of start, inclusive of end). For example, January 1 to January 3 = 2 days.
Does it account for leap years?
Yes. The calculator uses JavaScript Date objects which correctly handle leap years (Feb 29 in years divisible by 4, except centuries unless divisible by 400).
What are business days?
Business days are weekdays (Monday through Friday), excluding Saturday and Sunday. This calculator counts business days between the two dates. It does not account for public holidays.
Can I calculate a date in the past?
Yes. If the end date is before the start date, the calculator shows the absolute difference and notes that the dates are reversed.
How is the month difference calculated?
Total months are calculated as the difference in year×12 + month values. The exact breakdown (years, months, days) accounts for varying month lengths. For example, Jan 31 to Mar 1 = 1 month, 1 day.
Does it include both start and end dates?
The calculation is end minus start, so the start date is not included in the count. From Jan 1 to Jan 1 = 0 days. From Jan 1 to Jan 2 = 1 day.