Days Between Dates Calculator
Pick two dates to calculate the exact difference in days, weeks, hours, months, and years.
Total Days
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Total Weeks
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Total Hours
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Years + Months
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How the Day Count Works
The number of days between two dates is calculated by subtracting the earlier date from the later one. counting every calendar day in between, including weekends. The result is a simple integer: if you pick June 1 and June 19, the difference is 18 days. Whether you include the start date, the end date, or both depends on context. Legally, contract terms usually count from the day after signing ("day 1" is tomorrow). This calculator follows the standard mathematical definition: June 1 to June 19 = 18 days (not 19).
Leap years are handled automatically. A year is a leap year if it is divisible by 4, except for century years, which must be divisible by 400. So 2000 was a leap year, but 1900 was not. This matters for long date ranges that cross a February 29.
Expressing the Difference in Other Units
Once you have a day count, converting to other units is straightforward:
- Weeks: divide by 7 (e.g. 100 days = 14 weeks and 2 days)
- Hours: multiply by 24 (100 days = 2,400 hours)
- Minutes: multiply by 1,440 (100 days = 144,000 minutes)
- Months: approximate as days ÷ 30.4375 (average month length)
Example: from January 15 to October 31 is 289 days, which is 41 weeks and 2 days, or approximately 9.5 months.
Common Reasons to Count Days
Contract and legal deadlines are the most common use: statutes of limitations, notice periods, payment terms (Net 30, Net 60), and lease expirations all depend on exact day counts. A Net 30 invoice issued on June 5 is due July 5. 30 days later.
Project planning uses day counts to work backward from a deadline. If a product launch is September 1 and today is June 19, there are 74 days to work with. Divide by sprint length to see how many development cycles remain. Event countdowns. weddings, vacations, exams. are another everyday use. For personal milestones, counting days since a significant date (sobriety, a health journey, starting a habit) provides a concrete sense of progress that "X months" can obscure.