Date Difference Calculator
Find the exact time between two dates in years, months, and days, or add and subtract days, weeks, months, and years from any date. Use business-day and inclusive-counting options when needed.
Last updated September 6, 2026
How to Use the Date Calculator
Use the calculator in one of two ways.
- Difference Between Dates: enter a start date and end date.
- Choose whether the end date should be included in the day count.
- Optionally count Monday–Friday business days.
- View the exact calendar difference and total days.
Add or Subtract a Date
To move forward or backward from a starting date:
- Choose a starting date.
- Select Add or Subtract.
- Enter an amount and choose days, weeks, months, or years.
- Review the resulting date and day of the week.
All date calculations run directly in your browser.
Calendar Difference vs. Total Days
There are two useful ways to describe the gap between dates.
Calendar difference expresses the span as completed years, months, and remaining days, such as 2 years, 7 months, and 22 days.
Total days expresses the same elapsed span as one absolute number, such as 965 days.
Because months and years have different lengths, you should not convert total days into “exact months” or “exact years” simply by dividing by 30 or 365.
Should the End Date Be Included?
By default, date differences usually measure elapsed time between the start of one date and the start of another, so the end date is not counted as an additional day.
Enable “Include end date” when both boundary dates should count. For example, January 1 through January 3 is 2 elapsed days, but 3 calendar dates when counted inclusively.
Contracts, legal deadlines, travel rules, and benefit periods may use their own counting conventions, so follow the applicable rule for official decisions.
How Months and Leap Years Are Handled
The calculator uses real Gregorian calendar dates. Months may contain 28, 29, 30, or 31 days, and leap years include February 29.
When adding a calendar month, the calculator keeps the same day number when that date exists in the target month. If it does not exist, the result is clamped to the final day of that month.
Example:
January 31 + 1 month = February 28, or February 29 in a leap year.
Frequently asked questions
How do I calculate the number of days between two dates?
Enter the start and end dates. The calculator shows the exact calendar difference plus the total number of elapsed days.
What is the difference between total days and years/months/days?
Total days is one absolute elapsed count. Years/months/days is a calendar breakdown based on real month and year boundaries.
Does the date calculator include the end date?
Not by default. Enable “Include end date” when both boundary dates should be counted.
Can I count only business days?
Yes. Business-day mode counts Monday through Friday and skips weekends. Public holidays are not excluded unless explicitly supported.
What happens when I add one month to January 31?
The result is clamped to the last valid day of February: February 28, or February 29 in a leap year.
Does the calculator handle leap years?
Yes. It uses actual Gregorian calendar dates, including February 29 in leap years.
Are my dates uploaded?
No. Calculations run locally in your browser.