Date Calculator – Add/Subtract Days & Business Day Counter
Add or subtract dates, count exact differences, and compute Monday-Friday business days.
About the Date Calculator – Add/Subtract Days & Business Day Counter
The Date Calculator computes elapsed time between dates, project deadlines, and Monday–Friday business day totals.
Date Calculation Standards
Difference = End Date - Start Date (in days)
Business Days = Total Monday through Friday dates within range.
Worked Step-by-Step Examples
Example: Add 45 days to Jan 15, 2026
1. January has 31 days (16 days remaining) 2. February 2026 has 28 days 3. 45 - 16 - 28 = 1 day into March Result: March 1, 2026
Frequently Asked Questions
In v1, business days count Monday through Friday. Local public holidays are not automatically excluded as holiday calendars vary by jurisdiction.