Calculate the exact number of days, weeks, months, and years between any two dates — including business days and weekends.
The simplest approach is to count the number of days from the start date to the end date. To convert that into weeks, divide by 7. For months and years, you need to account for the varying lengths of months (28–31 days) and leap years, which is why a calculator is more reliable than mental arithmetic.
Business days (also called working days) are Monday through Friday, excluding weekends. They don't automatically exclude public holidays — those vary by country and region. The business day count above excludes Saturdays and Sundays only.
Common uses: calculating a payment due date, determining a deadline (e.g. "30 business days from today"), finding a date 90 days from an event, or working out a lease end date. The Add / Subtract tab handles all of these.
A leap year adds an extra day (Feb 29) to the calendar every 4 years, with exceptions for century years not divisible by 400. This calculator accounts for leap years automatically — so a span crossing Feb 29 will correctly include that day in the total count.
Because months have different lengths (28–31 days), expressing a duration in months can produce a decimal. For example, 45 days is roughly 1.48 months. The calculator shows the exact breakdown of complete years, complete months, and remaining days to avoid ambiguity.
By default, the day count is inclusive of the start date but exclusive of the end date — the standard mathematical interpretation. If you need to count both endpoints (as you might for event duration), tick the "Exclude start and end dates" option and add 2, or use the result as-is for total elapsed days.