Date Difference Calculator

Calculate the exact days, weeks, months, and years between any two dates

Instant | 100% client-side

Quick Calculations

Day Breakdown

Quick Tips

  • Use Swap to reverse start and end dates
  • Business days excludes weekends (Sat & Sun)
  • Switch to Add/Subtract tab to find future or past dates
  • Handles leap years and month-length variations

100% Private

All date calculations happen locally in your browser. No data is sent to any server.

How Date Difference Calculations Work

Understanding the math behind counting days between dates

Calculating the difference between two dates seems simple, but the Gregorian calendar introduces complexity: months have varying lengths (28–31 days), leap years add an extra day every 4 years (with century exceptions), and business day calculations must exclude weekends.

Our calculator handles all these edge cases accurately. It computes the precise number of calendar days, then breaks that down into years, months, weeks, and remaining days. Business days are calculated by counting only Monday through Friday, and the day-of-week breakdown shows you exactly how many of each weekday fall within your range.

Calendar Days

Total number of days between two dates, including weekends and holidays. This is the most common way to express date differences.

Business Days

Weekdays only (Monday–Friday), excluding Saturdays and Sundays. Essential for project planning, deadlines, and contract terms.

Date Arithmetic

Add or subtract days, weeks, months, and years from any date. Find deadlines, due dates, expiration dates, and milestone dates instantly.

Common Date Calculations

Popular uses for date difference calculators

Project Deadlines

Calculate how many business days remain until a project deadline, or determine a realistic end date given a number of working days.

Contract & Lease Periods

Verify the exact duration of contracts, leases, or subscription periods. Know precisely how many days, months, or years remain.

Age & Anniversary Calculations

Find exact age in days, calculate days until a birthday or anniversary, or determine how many days old you are.

Travel & Event Planning

Count days until vacation, determine trip duration, or calculate how many weekends fall within a travel period.

Frequently Asked Questions

Common questions about date calculations

Enter your start date and end date in the fields above. The calculator will instantly show the difference in total days, weeks, months, and years, along with business days and weekend days. You can also see the breakdown in hours, minutes, and seconds.
Yes. The calculator shows both total calendar days and business days (Monday–Friday only). It also displays the number of weekend days (Saturdays and Sundays) and a per-weekday breakdown showing how many of each day of the week fall in your range.
The calculator correctly accounts for leap years, including the century rule (years divisible by 100 are not leap years unless also divisible by 400). February 29th is properly handled in all calculations, both for date differences and date arithmetic.
Yes. Switch to the Add/Subtract Days tab, enter a start date, then specify the number of years, months, and/or days to add or subtract. The calculator will show you the resulting date, day of the week, and how far it is from today.
A regular year has 52 weeks and 1 day (365 days). A leap year has 52 weeks and 2 days (366 days). This is why the same date falls on a different day of the week each year.
The business day calculation excludes Saturdays and Sundays but does not account for public holidays, which vary by country and region. For precise business-day calculations including holidays, you may need to manually subtract applicable holiday dates.