Calculate Difference Between Two Dates

Searching calculate difference between two dates usually means you need the time between a start date and an end date. The answer can be shown in total days, weeks, months, years, or business days.

Use our Date Calculator or Days Calculator for quick results.

Basic Day Difference

Date difference = End date - Start date

Example:

May 1, 2026 to May 15, 2026 = 14 days between dates.

If you count both May 1 and May 15 inclusively, the count is 15 days.

Weeks Between Dates

Divide total days by 7.

Example:

28 days / 7 = 4 weeks

If the result does not divide evenly, you can show weeks plus remaining days.

Months and Years Between Dates

Months and years are trickier because months have different lengths and leap years can add a day. Calendar month difference counts full month changes, not just day totals.

Example:

January 15 to March 15 = 2 calendar months.

January 31 to February 28 is usually treated as less than one full calendar month depending on the rule used.

Business Days

Business days usually exclude Saturdays and Sundays. Some calculations also exclude holidays. Always check the rule for shipping, legal, payroll, or project deadlines.

Common Mistakes

Inclusive vs exclusive counting can add or subtract one day.

Assuming every month has 30 days can be wrong.

Forgetting leap years affects long ranges.

The Bottom Line

To calculate the difference between two dates, choose the start date, end date, and output type. For precise calendar and business-day results, use a calculator.

Try the Date Calculator for date math and the Days Calculator for day counts.

How to Calculate: Step-by-Step Guide

1

Select the start date

Choose the first date in the range.

2

Select the end date

Choose the second date in the range.

3

Choose output format

Decide whether you need days, weeks, months, years, or business days.