Mastering Date Calculations
From planning project deadlines and notice periods to counting the exact days until your next vacation. This tool handles the complexities of the Gregorian calendar, including leap years and varying month lengths, so you don't have to.
Examples
Common date calculations and their results:
| Start Date | Operation | Result (Calendar) | Result (Business) |
|---|---|---|---|
| Friday | +1 Day | Saturday | Monday |
| Friday | +3 Days | Monday | Wednesday |
| Jan 1 | to Jan 31 | 30 Days | 20-22 Days (varies) |
Calendar vs. Business Days
Most calculations need to account for weekends. Toggle 'Exclude Weekends' to calculate strict Business Days (Monday-Friday). This is essential for work deadlines, shipping estimates, and legal notice periods.
Inclusive vs. Exclusive
By default, 'Days Between' calculates the duration *elapsed* (Exclusive). If you need to include the start date in the count (e.g., for day-rate billing), simply add 1 to the final result.
Frequently Asked Questions
Q:How do I calculate the number of days between two dates?
Select 'Days Between Dates' mode, choose your Start Date and End Date using the calendar pickers. The calculator will instantly show the total days (and weeks) between them. Use the 'Exclude Weekends' checkbox to see only working days.
Q:Does this date calculator account for leap years?
Yes, absolutely. Our algorithm follows the Gregorian calendar rules strictly, so February 29th is correctly counted in any range crossing a leap year (like 2028).
Q:Can I add months or weeks to a specific date?
Yes. In 'Add / Subtract Days' mode, simply change the unit dropdown from 'Days' to 'Weeks', 'Months', or 'Years'. You can then add (e.g., +3 Months) or subtract (e.g., -2 Weeks) from any starting date.
Q:What are 'Business Days' in this calculator?
Business Days (or Working Days) refer to Monday through Friday, excluding Saturday and Sunday. When you check 'Exclude Weekends', the result will only count these weekdays, which is perfect for project planning.
Q:How do I verify a 90-day deadline?
Enter today's date in 'Add / Subtract' mode, ensure the operator is set to 'Add', type '90' in the quantity field, and select 'Days'. The result will be your exact deadline date.