Hours calculator: work hours between two times

The calculator works in 24-hour format and splits each time into two fields (hour and minutes), which keeps a.m./p.m. confusion out of the picture — 5:00 p.m. is simply hour 17.

1. Start time: the hour (0-23) and minutes (0-59) when you clock in. For 8:30 a.m.: hour 8, minutes 30. 2. End time: when you clock out. For 5:00 p.m.: hour 17, minutes 0. If you finish after midnight (an overnight shift), just enter the actual end time — the calculator detects the midnight crossover automatically. 3. Break: the unpaid minutes you want to deduct, typically lunch. U.S. federal law does not require meal breaks, but when employers offer bona fide meal periods of 30 minutes or more, they are usually unpaid — which is exactly why you subtract them here. 4. Results: you get the total as a decimal (7.50 = seven and a half hours), ready to multiply by your hourly rate for payroll, and the breakdown in hours and minutes (7 h 30 min) for your timesheet.

One detail: if the break is longer than the time between start and end, the result clamps to 0 instead of going negative.

Everything is computed in minutes — the most reliable way to do arithmetic with times of day. The formula in plain text:

start_minutes = start_hour × 60 + start_minute end_minutes = end_hour × 60 + end_minute raw = end_minutes − start_minutes if raw < 0 → raw = raw + 1440 (the shift crosses midnight; 1440 is the number of minutes in a day) net = raw − break (floored at 0) decimal_hours = net ÷ 60 hours = floor(net ÷ 60); minutes = net − hours × 60

Worked numeric example: clock in at 8:30 a.m., clock out at 5:00 p.m., 60-minute lunch.

• start_minutes = 8 × 60 + 30 = 510
• end_minutes = 17 × 60 + 0 = 1,020
• raw = 1,020 − 510 = 510 minutes
• net = 510 − 60 = 450 minutes
• decimal_hours = 450 ÷ 60 = 7.50 hours
• breakdown: 7 h 30 min

At $18 an hour, that day is worth 7.5 × 18 = $135 gross. The 1,440-minute step is what makes overnight shifts work: from 10 p.m. to 6 a.m., raw comes out at −960; adding 1,440 leaves 480 minutes, i.e. 8 hours before the break is deducted.

Three common situations in the U.S., all solved with the same formula:

• Standard 9-to-5 with lunch: clock in 8:30 a.m., clock out 5:00 p.m., 60-minute lunch. Raw: 1,020 − 510 = 510 minutes; net: 450 → 7.50 hours (7 h 30 min). At $18 an hour, that is $135 for the day.
• Part-time morning shift: in at 8:15 a.m., out at 2:45 p.m., 20-minute break. Raw: 885 − 495 = 390; net: 370 → 6.17 hours (6 h 10 min).
• Overnight shift: in at 10:00 p.m., out at 6:00 a.m., 45-minute break. Raw goes negative (360 − 1,320 = −960); add 1,440 → 480; net: 435 → 7.25 hours (7 h 15 min).

Decimal-format tip: minutes get divided by 60, not written after the point. 7 h 30 min is 7.50 hours, not 7.30 — the single most common timesheet mistake. And for payroll context: a two-week timesheet of ten 7.5-hour days adds up to exactly 75 hours; under the FLSA, overtime pay at time and a half only kicks in beyond 40 hours in a single workweek, so a 37.5-hour week stays at the regular rate.

This hours calculator does it instantly: enter your start time, end time and break minutes, and you get the exact total in hours and minutes plus the decimal format (7.50 instead of 7 h 30 min) that payroll software and timesheets use. That decimal number matters: multiply it by your hourly rate and you know exactly what your paycheck should say — 7.5 hours at $18 an hour is $135 before taxes. It also handles overnight shifts that cross midnight, so a 10 p.m. to 6 a.m. shift comes out right every time.