Hours Between Dates Calculator

The calculator constructs two JavaScript Date objects from the separate year, month, day, hour, and minute inputs, then subtracts the start timestamp from the end timestamp to get total elapsed milliseconds. That raw millisecond difference is converted to each output unit by dividing by the appropriate constant: 3,600,000 ms per hour for total hours, 60,000 ms per minute for total minutes, and 86,400,000 ms per day for total days. The formatted hours-and-minutes output uses Math.floor on the total hours and the modulo of milliseconds within an hour to isolate the remaining minutes. The calculation inherently handles all calendar complexities — month boundaries, leap years, and daylight saving time changes are managed by the Date object.