Work hours calculator

How to calculate hours between two times

The work hours calculator answers one question quickly: how long was I at work, and how much of that was paid? Put in when you started, when you finished and how long your unpaid break was. It does three steps:

1. Put both times on a 24-hour clock. 8:00 AM stays 8:00, and 5:00 PM becomes 17:00.
2. Subtract the start from the end. 17:00 − 8:00 = 9 hours. If the end is earlier than the start, the shift ran past midnight, so add 24 hours first.
3. Take off the unpaid break. 9 hours minus a 30-minute lunch is 8 hours 30 minutes, or 8.5 decimal hours.

Add more rows for a second job, a split shift or a few days in a row, and the total updates as you type. It works as a plain hours calculator too, for anything with a start and an end.

How many hours is a typical shift?

The questions people search most are about common shift times. Here are the answers, before and after the two usual lunch breaks:

You can type times the way you would say them. In 12-hour mode, “8” and “5” are read as 8 AM to 5 PM, because a 21-hour shift is much less likely than a normal day; the calculator rewrites the times when you leave the field so you can see how it read them. It also takes 830, 8:30, 8:30pm, 20:30 and 8.5 (decimal hours, so 8:30). In 24-hour mode nothing is guessed, and 8 to 5 is an overnight shift.

Overnight shifts

A shift that starts before midnight and ends after it has an end time that looks earlier than the start. The calculator treats that as the next day: 11:00 PM to 7:30 AM is 8 hours 30 minutes, and with a 30-minute break, 8 hours. On a 24-hour clock that is 23:00 to 07:30, and the sum is (24:00 − 23:00) + 7:30.

For federal overtime, the workweek is a fixed period of 168 hours that can start on any day and at any hour (US Department of Labor, overtime pay). A night shift that crosses the start of your employer’s workweek can fall partly in one week and partly in the next when overtime is worked out, so check when yours starts. A shift longer than 24 hours cannot be entered as one row; split it into two.

Rounding to the quarter hour

Many time clocks round each punch instead of recording the exact minute. For federal enforcement, the US Department of Labor accepts recording times to the nearest 5 minutes, tenth of an hour (6 minutes) or quarter hour, as long as over time it does not leave employees unpaid for the time they actually worked (29 CFR 785.48(b)). Rounding to the quarter hour is often called the 7-minute rule:

• 8:07 AM becomes 8:00 AM: 7 minutes past, so it rounds down.
• 8:08 AM becomes 8:15 AM: 8 minutes past, so it rounds up.
• 4:52 PM becomes 4:45 PM: 7 minutes past the quarter, so down.
• 4:53 PM becomes 5:00 PM: 8 minutes past the quarter, so up.

Choose 5, 6 or 15 minutes above the result to round each start and end time the same way. The calculator rounds the punches, not the total, because that is what a time clock does. Rounding that keeps landing in the employer’s favour does not meet that condition, and state law can differ. This is arithmetic, not legal advice.

From hours to pay

Add an hourly rate and the calculator multiplies it by the decimal hours: 8 hours 30 minutes at $18 an hour is 8.5 × $18 = $153.00 before tax. It does not add overtime, because overtime depends on the whole workweek. For a full week with overtime, use the timesheet calculator, which splits regular and overtime hours.

Written and maintained by the DoneThat team. The examples match the calculator code, and the rounding rule was last checked against its source on 3 November 2026.

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