Date Difference Calculator
Calculate the exact number of days, months, and years between two dates. Includes business days, weekend count, and duration breakdown.
How Day Counting Works
The calculator counts each day between your start and end dates. When "Include end date" is checked, the end date is included in the total, making it useful for date-range calculations like rental periods or project timelines.
Business Days Explained
Business days are Monday through Friday, excluding weekends. This calculator counts business days and weekend days separately, making it easy to plan work schedules, shipping dates, or project milestones.
Age & Birthday Calculator
Enter a birthday in the optional field and set the start date to that birthday to see your exact age in years, months, and days. Use the "Next Birthday" preset to find out how many days until your next birthday.
Frequently Asked Questions
To calculate the number of days between two dates, subtract the start date from the end date. The result is the difference in milliseconds, which you divide by 86,400,000 (1000 * 60 * 60 * 24) to get the number of days. For months and years, the calculation accounts for varying month lengths and leap years.
Business days are weekdays from Monday through Friday, excluding weekends (Saturday and Sunday). When calculating business days between two dates, only these five days are counted. Different countries may have different definitions, but this calculator uses the standard Monday-Friday business week.
Yes, you can enter any start and end dates to calculate the difference. You can also use the preset buttons to quickly add 30, 60, or 90 days, or 1 year from your start date. The calculator supports dates from January 1, 1970 to December 31, 2099.