π Date Difference Calculator
Find the exact difference between two dates in days, weeks, months, and years.
Total Days
How to Use This Tool
Enter a start date and an end date. The calculator shows the total days between them along with weeks, months, years, business days (Monday to Friday), and total hours. Click Today as Start to use today's date as the starting point.
Enter or pick a Start Date using the date input field.
Enter or pick an End Date. The order does not matter: the calculator handles either direction.
Click Calculate to see the full breakdown, or click Today as Start to set the start date to today automatically.
Read the results: calendar days, weeks, months, business days, weekend days, and total hours.
Calendar Days vs Business Days: When Each Matters
Calendar days count every day in the span including weekends and holidays. Business days (also called working days) count only Monday through Friday. The difference matters significantly for planning. A project that is 30 calendar days long only has about 21 business days of actual working time if it runs through a normal week pattern. Legal and financial deadlines are almost always specified in business days: a "10 business day" response window is two full calendar weeks. This calculator counts business days by iterating through each day in the range and checking whether it falls on a Saturday (day 6) or Sunday (day 0), then excluding those. Public holidays are not excluded because they vary by country and region, so you need to subtract those manually based on your location. When quoting a project deadline to a client, the distinction matters: telling someone a project will take 10 days implies they will have the result by next Friday or Monday, but if some of those are weekend days, the actual delivery is later. Use the business days figure for any communication where working time is what counts.
Common Use Cases
Frequently Asked Questions
How are business days calculated?
Business days = total days minus Saturdays and Sundays. Public holidays are not automatically excluded (they vary by country and region).
How do you count months between dates?
Month counting compares the month and year of both dates. Partial months are handled based on whether the end day is >= the start day.
What is the difference between calendar days and working days?
Calendar days count every day including weekends. Working/business days only count MondayβFriday.
Can I calculate dates in the future?
Yes β enter any two dates regardless of whether they are past, present, or future.
What is the longest possible date difference?
JavaScript's Date object supports dates from -100,000,000 to +100,000,000 days from January 1, 1970 β covering millions of years in both directions.