Use cases
Durations, deadlines, warranty periods, and simple “how many days between” questions.
Notes
This tool works with calendar days only—no hours or minutes. If you need time-of-day precision across daylight saving changes, use a full date-time tool. Leap years and month lengths follow your browser’s date logic.
How to use it
Pick either “difference between two dates” or “start date plus N days.” In difference mode, choose two dates and get the number of days between them. In add mode, pick a start date and how many days to add. The date control may look different on phone vs desktop, but the selected day is what gets counted.
Related information
The US often writes month/day/year; many other regions use day/month/year or ISO year-month-day. How the field looks can follow your system language; the day you pick is still the same for the calculation.