Date Duration Calculator
Calculate the exact number of days, weeks, and months between two dates. Includes options for business days only and holiday exclusions.
About
Project planning, contract terms, and visa applications often depend on precise day counts. A simple subtraction of dates can be misleading if it ignores leap years, weekends, or public holidays. This tool provides a granular breakdown of time duration, ensuring you know exactly how many "working days" exist between a start and end point. It is particularly useful for HR professionals calculating leave or project managers estimating sprint velocities.
Formulas
The core calculation converts both timestamps to Universal Coordinated Time (UTC) to avoid timezone offsets affecting the day count.
For business days, the algorithm iterates through the range:
Reference Data
| Time Unit | Conversion Ref | Notes |
|---|---|---|
| 1 Year | 365 or 366 days | Leap years occur every 4 years (mostly) |
| 1 Month | 28, 29, 30, 31 days | Irregular duration makes "Month" counts approx in some contexts |
| 1 Week | 7 Days | Constant |
| Business Week | 5 Days | Mon-Fri usually |
| Q1 | Jan 1 - Mar 31 | 90 or 91 days |
| Q2 | Apr 1 - Jun 30 | 91 days |