Date Difference Calculator
Calculate the exact number of days, weeks, months, and years between any two dates. See business days, weekends, and detailed time breakdowns.
Common Time Periods
How Date Calculation Works
Calculating the difference between two dates involves accounting for varying month lengths, leap years, and whether to include or exclude the end date.
Include vs Exclude End Date
Include end date: Counts both the start and end dates. If you're counting days for an event that spans Jan 1 to Jan 3, that's 3 days total.
Exclude end date: Counts days between but not including the end date. Jan 1 to Jan 3 would be 2 days.
Business Days
Business days exclude weekends (Saturday and Sunday). This is useful for calculating work schedules, project timelines, or shipping estimates.
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Uses for Date Difference Calculation
Shipping & Delivery
Calculate delivery windows and shipping timelines. Know exactly how many business days until a package arrives.
Project Planning
Plan project timelines, set milestones, and track deadlines by calculating working days between dates.
Travel Planning
Calculate trip duration, days until departure, or how long until your vacation ends.
Financial Calculations
Determine loan periods, investment durations, or days until payment due dates.
Academic Planning
Count school days, days until graduation, or duration of semesters and breaks.
Medical & Health
Track medication schedules, days since surgery, or time until follow-up appointments.
Frequently Asked Questions
Should I include the end date in my calculation?▼
It depends on your use case. If you're counting days for an event (like a conference from Day 1 to Day 3), include the end date. If you're calculating time until something (days until Christmas), exclude it. Our calculator lets you choose.
How are business days calculated?▼
Business days count only Monday through Friday, excluding weekends. Our calculator doesn't account for public holidays as these vary by country and region. For holiday-aware calculations, you'd need to manually subtract holidays.
Does this account for leap years?▼
Yes! The calculator automatically handles leap years. February 29th is properly counted when calculating differences that span leap years.
Why does the month calculation sometimes seem off?▼
Months have varying lengths (28-31 days), so "1 month" isn't always 30 days. Our calculator uses calendar months, so January 15 to February 15 is exactly 1 month, even though it's 31 days.
Can I calculate dates in the past?▼
Absolutely! You can calculate the difference between any two dates, past or future. The calculator will automatically handle the direction and give you the absolute difference.
How accurate is the seconds calculation?▼
The calculation is accurate to the day level. For simplicity, we assume each day has exactly 24 hours (86,400 seconds). This doesn't account for daylight saving time transitions or leap seconds, which are rarely significant for most use cases.