What this tool does
Calculate the difference between clock times or dated times, subtract an optional break, and compare hours:minutes, minutes and decimal hours.
How to use it
- Choose Times only for a same-day or one-midnight interval, or Include dates for a dated interval.
- Enter start and end times in 24-hour format. In date mode, select the actual start and end dates.
- Enter the break in whole minutes, or leave it blank for zero. The break cannot exceed the full interval.
- Calculate, then read the full interval, deducted break and remaining duration. Editing any input clears the previous result and copy action.
Method
For times only, subtract start minutes from end minutes; an earlier end adds 1,440 minutes only when crossing midnight is allowed. With dates, subtract the two validated calendar date-times on a fixed 24-hour-day scale. Net minutes = full minutes − break minutes. Divide net minutes by 60 for decimal hours; the quotient and remainder form hours:minutes. Decimal hours are rounded to at most six places.
Worked example
From 2026-08-31 23:30 to 2026-09-02 01:15 is 1,545 minutes. Subtracting a 45-minute break leaves 1,500 minutes, 25:00 or 25 decimal hours. For times only, 23:30 to 01:15 minus 15 break minutes leaves 90 minutes: 01:30 or 1.5 hours, not 1.30 hours.
Common uses
- Comparing study sessions after chosen breaks
- Planning events that span several dates
- Converting a duration to minutes or decimal hours
Limitations
This is calendar and clock arithmetic, not a payroll or legal working-time calculation. It does not apply time zones, daylight-saving transitions, overtime, paid-break rules or payroll rounding. The browser time zone does not alter the difference; use the time-zone tool for location-aware instants. Times-only mode crosses at most one midnight and equal times mean zero. Date mode accepts valid years 0001–9999 and an end no earlier than the start.
FAQ
Does it automatically decide which breaks to subtract?
No. Enter the total break minutes you want to deduct. Blank means zero; negative, fractional or excessive breaks are rejected.
How do I calculate exactly 24 hours?
Choose Include dates and the same time on consecutive dates. In Times only mode, equal start and end still mean zero.