About this tool
The Days Between Dates calculator counts the exact number of days from a start date to an end date and then expresses that span every way people usually need it: weeks and days, months and days, years, months, and days, weekdays (Monday to Friday) versus weekend days, and total hours and minutes. An 'include end date' option switches between the difference convention (Jan 1 to Jan 2 is 1 day) and the inclusive convention used for hotel nights, rental periods, and payroll (Jan 1 to Jan 2 is 2 days). It is built for deadlines, project schedules, leave calculations, age-in-days questions, and anniversary counts.
How it works
Both inputs are parsed as local calendar dates at midnight, and the day count is Math.round((end - start) / 86,400,000), which is immune to the 23- and 25-hour days that daylight-saving transitions create. With 'include end date' checked, 1 is added. Weekdays are counted arithmetically: every full 7-day block contributes 5 weekdays, and the leftover days are checked one by one against the starting weekday. The months-and-days and years-months-days figures use calendar anniversaries (Jan 31 plus one month is Feb 28 or 29), so they match what a person would count on a wall calendar.
Frequently asked questions
Should I include the end date?
Use the difference (unchecked) when you want the number of nights, the number of days until something, or an age in days. Check 'include end date' when both endpoints are part of the period, such as a rental from the 1st to the 5th (5 days) or counting the days of a full year (Jan 1 to Dec 31 is 366 days in 2024 inclusive).
How many weekdays are in a year?
A full year has 260, 261, or 262 weekdays. 2024 has 262 (it is a leap year starting on Monday, so its two extra days beyond 52 weeks are Monday and Tuesday). A non-leap year has 261 if it starts on a weekday and 260 if it starts on a weekend.
Why is the weekday count not the same as business days?
Weekdays here are simply Monday through Friday. Business days also remove public holidays, which vary by country and employer. Use the Business Days Calculator on this site for a count that excludes US federal holidays.
Does the calculator handle daylight-saving time and leap years?
Yes. Dates are handled at local midnight and the millisecond difference is rounded, so a DST change never creates a fractional day. Leap days are counted naturally: 2024-02-28 to 2024-03-01 is 2 days, while the same span in 2023 is 1 day.