Date Difference & Business Days Calculator
Find the difference and business days between two dates, or add and subtract years, months, weeks, and days.
How the Date Calculator works
The calculator normalises both dates to midnight UTC before comparing them, so daylight-saving changes never add or remove an hour from the result. The total is divided into weeks, and a calendar-aware walk produces the months-and-days breakdown.
Every day in the range is classified by weekday, so you also get a count of Monday–Friday business days and Saturday–Sunday weekend days. In Add / Subtract mode, offsets are applied largest unit first, and if the target month is shorter the day is clamped to that month’s last day.
Formulas used
- Total days
days = (end − start) ÷ 86,400,000 ms- Weeks
weeks = days ÷ 7Shown with the remaining days.- Business split
weekdays + weekend days = total days
How to use the Date Calculator in 3 steps
Step 1
Choose Date Difference or Add / Subtract mode at the top of the tool.
Step 2
Pick a start date and an end date, or enter the years, months, weeks and days to offset.
Step 3
Press Calculate to see total days, weeks, months, weekdays and weekend days, or the resulting target date.
Frequently asked questions
How many business days are between two dates?
Enter both dates and press Calculate. The result card lists the weekdays (Monday to Friday) and weekend days (Saturday and Sunday) in the range. Public holidays are not subtracted because they vary by country.
Is the end date included in the day count?
By default the start date is counted and the end date is not, which matches how most contracts and deadlines are measured. Turn on the include end date option to count both days.
What happens when I add one month to 31 January?
February has no 31st, so the result is clamped to the last day of February: 28 February, or 29 February in a leap year.