Calculating Span Between Dates
Date differences are derived by subtracting UTC Unix Epoch millisecond representations. This yields milliseconds, which are then sequentially divided into days, weeks, or standard calendar year/month intervals.
If you choose to **Include the End Date**, the calculator automatically aggregates an additional unit:
Frequently Asked Questions
Calendar months range from 28 to 31 days. Our high-fidelity parser calculates the exact calendar difference day-by-day (e.g. from March 15 to April 15 is exactly 1 month regardless of whether March has 31 days), ensuring true calendar accuracy compared to flat averages.
The standard calendar difference represents all calendar days. For project management tasks, you can divide total days by 7 and multiply by 5 to estimate typical working days (excluding national holidays and custom weekends).