Days Between Dates Calculator
Easily find out exactly how much time has passed or remains between any two dates.
🏆 Calculating Time Between Dates
Everything you need to know about using this calculator and the math behind it.
How it Works
Determines the absolute difference in days between a start date and an end date, strictly accounting for calendar rules like leap years.
The Formula
Difference = Absolute(Date 2 - Date 1) in milliseconds, converted to days.
Pro Tip
Perfect for counting down to a vacation, tracking project deadlines, or calculating the duration of an event.
Frequently Asked Questions
How are leap years handled in date calculations? +
Leap years occur every 4 years (years divisible by 4), except century years (divisible by 100) must also be divisible by 400. So 2000 was a leap year; 1900 was not. Our calculator precisely accounts for these rules using the Gregorian calendar. When a date span crosses a leap year's February 29, that extra day is included in the day count, ensuring accuracy over multi-year calculations.
What is the difference between calendar days and business days? +
Calendar days count every day including weekends and holidays. Business days (also called working days) count only Monday through Friday, excluding weekends. Federal holidays are typically also excluded. For contracts and legal deadlines, terms like "within 30 days" mean calendar days unless specified otherwise. Check your specific jurisdiction's rules for legal timelines as definitions can vary.
How do I calculate the number of weekdays between two dates? +
A quick method: divide total calendar days by 7 to get full weeks, multiply by 5 for weekdays, then manually add the remaining partial week's weekdays. More precisely, use a programming language or spreadsheet function like NETWORKDAYS in Excel/Google Sheets that handles this automatically including holiday exclusions. Our date calculator can show both calendar and weekday counts.
What is the ISO 8601 date format? +
ISO 8601 is the international standard for representing dates: YYYY-MM-DD (e.g., 2024-12-25 for December 25, 2024). It avoids ambiguity between US format (MM/DD/YYYY) and European format (DD/MM/YYYY) — both could interpret 01/02/03 differently. ISO 8601 is used in software, databases, APIs, and international business communication. It also sorts chronologically when used in file names.
How many days until a common event? (Quick reference) +
Use the calculator above to count down to any event. Common planning horizons: job offer deadlines are usually 3–7 days; apartment lease breaks typically require 30–60 days notice; wedding venue bookings usually need 12–18 months ahead; passport applications take 6–12 weeks in normal times; mortgage closing typically takes 30–45 days. Enter your target date above for a precise countdown including weeks and months.