📅 Date Difference Calculator

Calculate the exact difference between two dates in days, weeks, months, and years. Also add or subtract days from a date.

Date Difference

Total Days
0
Years
0
Months
0
Days Remainder
0
Total Weeks
0
Total Hours
0
Weekdays Only
0
Weekend Days
0
Direction
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Add / Subtract Days from a Date

Result Date
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Day of Week
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Week Number
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How Date Calculations Work

Dates are internally stored as milliseconds since January 1, 1970 (Unix timestamp). The difference between two dates in milliseconds can be converted to days by dividing by 86,400,000 (milliseconds per day).

Common Use Cases

  • Project planning: How many working days until the deadline?
  • Anniversaries: How many days since a special event?
  • Legal deadlines: 30, 60, or 90 days from a specific date
  • Contract durations: Length of a lease, employment period, or subscription
  • Age verification: Is a person at least 18 years old?
Why are weekday counts important? +
Many business and legal deadlines are counted in business days (Monday–Friday), excluding weekends and holidays. Knowing the number of weekdays between two dates helps with project scheduling, shipping estimates, and legal deadline calculations. Note: this calculator counts weekdays but not public holidays, which vary by country and region.
What is a Julian date? +
A Julian date (or Julian Day Number) is a continuous count of days since January 1, 4713 BC, used in astronomy and some computing systems. It differs from the Gregorian calendar we use daily. The "Julian calendar" (before the Gregorian reform in 1582) is also sometimes confused with this — they are distinct concepts.