How midnight rollover works
Convert both clock times to minutes after midnight. If the end is earlier than the start, add 24 hours to the end before subtracting. A 10:00 PM to 6:30 AM shift is therefore 8 hours 30 minutes before breaks, not a negative duration.
The main weekly calculator applies the same rollover logic and includes a Night Shift input mode. Explicit AM/PM or 24-hour values such as 22:00 and 06:30 reduce ambiguity.
Recording the shift on the correct date
A shift can cross a calendar date, a workday boundary, or even an employer’s fixed workweek boundary. Those concepts are not always identical. Follow the employer’s established payroll practice and preserve the actual start and stop timestamps.
Do not assume that working at night automatically creates federal overtime or premium pay. Under federal law, extra pay for nights is generally a matter of agreement, while hours above the applicable overtime threshold may require a premium.
- Use explicit AM/PM or 24-hour notation.
- Record the starting date alongside the times.
- Subtract a meal period only when it was genuinely off duty and unpaid.
- Check whether the shift crosses the employer’s workweek boundary.
- Add any contractual night differential separately from worked hours.
Common overnight time-card mistakes
The most frequent errors are treating the end time as the same morning, subtracting a paid rest break, assigning every hour to the wrong workweek, and forgetting that daylight-saving transitions can alter elapsed clock time.
This simple calculator assumes a normal 24-hour day. For a shift spanning a daylight-saving change, preserve timestamp and timezone records and use the employer’s approved system.