Shift Calculator

DateMath adds the hours to work and the unpaid break to the start time, because a break you are not paid for keeps you at work that much longer: 8 hours from 9:00 AM with a 30-minute lunch ends at 5:30 PM. Past midnight the clock starts again at 12:00 AM and the result says "the next day". To find the start, DateMath subtracts the same amount from the end time. Times are clock times without a time zone.

• US hours-worked rules. DateMath counts exact minutes and subtracts only the breaks you enter. The federal Fair Labor Standards Act rules count rest breaks of about 5 to 20 minutes as work time but not bona fide meal periods (ordinarily 30 minutes or more), and allow rounding clock times to the nearest 5 minutes, tenth or quarter of an hour only if employees are still paid for all the time they work. Source: 29 CFR 785.18, 29 CFR 785.19, 29 CFR 785.48.

DateMath's date math is tested against more than 100 cases worked out by hand. Every worked example and table on the site is computed with the same code the calculators run, so a page and its calculator can't disagree.

An 8-hour shift ends 8 hours after you start, plus any break you are not paid for. From 9:00 AM with a 30-minute unpaid lunch, that is 5:30 PM; with no break, 5:00 PM. The shift calculator does this sum for any start time, any number of hours and any break, so it works as an 8 hours shift calculator, an 8 hours work calculator and a clock-out calculator for longer or shorter days.

What you enter

• Start time, the time you clock in, in your device's time picker. In "Find the start time" mode you enter the end instead.
• Hours to work and minutes: 8 hours by default, or tap 4, 6, 8, 10 or 12 hours. These are the hours you are paid for.
• Unpaid break in minutes, such as a lunch you clock out for. Paid rest breaks are part of the hours to work, so leave them out.

What you get

The headline gives the clock-out time, with "the next day" when the shift runs past midnight. Below it you see the whole shift in 12-hour and 24-hour (military) time, the hours worked with their decimal for a timesheet, the break, and the time from in to out, which is the hours worked plus the break.

1. Start from the clock-in time on the 24-hour clock: 7:45 AM is 07:45.
2. Add the hours to work. 07:45 + 8 hours = 15:45.
3. Add the unpaid break. 15:45 + 45 minutes = 16:30, carrying 60 minutes into an hour when the minutes pass 59.
4. Go back to 12-hour time if you like: 16:30 is 4:30 PM.

When the sum passes 24:00, subtract 24 hours and the shift ends the next day. From 9:30 PM, 8 hours plus a 30-minute break reaches 30:00, which is 6:00 AM the next day. DateMath does the same steps, so the calculator and this page always agree.

The end of an 8-hour shift for common start times, with no break and with the most common unpaid breaks. Find your start time in the first column and your break across the top:

A 9-to-5 day is therefore 8 hours of work only with no unpaid break; with a 30-minute lunch, 8 hours of work from 9:00 AM end at 5:30 PM.

The same sum works for any length. From 7:00 AM, with no break and with a 30-minute unpaid lunch:

A shift of 7.5 hours is 7 hours 30 minutes: enter 7 in Hours and 30 in Minutes. Four 10-hour shifts or three 12-hour shifts add up to a 40-hour or 36-hour week; to total the real days of a week, use the time card calculator.

A shift that starts in the evening ends the next morning. The calculator rolls past midnight on its own and marks the end with "the next day"; on a timesheet that uses dates, the time out belongs to the next date.

The calculator uses clock time, so it doesn't add or remove the hour the clocks move on a daylight saving night. In most of the US the clocks spring forward on the second Sunday in March and fall back on the first Sunday in November, at 2:00 AM: on those nights an 8-hour shift really ends an hour later or earlier on the clock than shown.

Switch to "Find the start time" when the end is fixed, such as a store that closes or a bus you need to catch. The calculator subtracts the hours and the break from the end time:

Only an unpaid break moves the clock-out time. Under the federal Fair Labor Standards Act rules, rest breaks of about 5 to 20 minutes are paid work time, and a bona fide meal period, ordinarily 30 minutes or more and free of all duties, is not. So a shift with two paid 15-minute breaks and an unpaid 30-minute lunch has a 30-minute break here. State law and your employer's policy can add their own break rules, so enter what your schedule calls unpaid.

With more than one unpaid break, add them and enter the sum: a 30-minute lunch and a 30-minute dinner are a 60-minute break, and an 8-hour shift from 10:00 AM then ends at 7:00 PM.

• Planning a day. When you can leave, so you can book a pickup or an appointment.
• Checking a schedule. Whether a posted shift, such as 6:30 AM to 3:00 PM with lunch, really gives 8 paid hours.
• Building a schedule. The start time for each person so the shifts end when the store or the line closes.

Once the shift is worked, the hours calculator measures the hours between the real times in and out, and the hours to decimal calculator converts them for payroll. To add up several amounts of time, use the hours and minutes calculator; to find what time it will be a number of hours from now, the time calculator.