How to Subtract a Lunch Break From Your Hours

Most shifts aren't just a start time and an end time — there's a lunch break in the middle that doesn't count as paid work. Subtracting that break correctly is one of the most common things a timecard has to get right, and the maths is simple once you see it laid out.

The formula

Net working time = (end time − start time) − break length. The trick is doing the subtraction in minutes, then converting back to hours and minutes at the end, so you don't accidentally treat 90 minutes as "1 hour 90 minutes" instead of 1 hour 30 minutes.

1. Convert the start and end time to minutes since midnight.
2. Subtract start from end to get the gross shift length in minutes.
3. Subtract the break length (also in minutes) from that gross figure.
4. Convert the result back to hours and minutes: divide by 60 for hours, and the remainder is minutes.

Worked example: a 30-minute lunch

A shift runs from 9:00 AM to 5:00 PM with a 30-minute lunch.

• 9:00 AM to 5:00 PM = 8 hours = 480 minutes gross
• 480 minutes − 30 minutes = 450 minutes net
• 450 minutes = 7 hours, 30 minutes remainder
• Net working time: 7h 30m

Worked example: a 45-minute lunch on a longer shift

A shift runs from 8:00 AM to 5:30 PM with a 45-minute lunch.

• 8:00 AM to 5:30 PM = 9 hours 30 minutes = 570 minutes gross
• 570 minutes − 45 minutes = 525 minutes net
• 525 minutes = 8 hours, 45 minutes remainder
• Net working time: 8h 45m

Worked example: an irregular start time

Not every shift starts on the hour. A shift runs from 6:15 AM to 2:40 PM with a 30-minute lunch.

• 6:15 AM = 375 minutes since midnight
• 2:40 PM = 14:40 = 880 minutes since midnight
• 880 − 375 = 505 minutes gross
• 505 − 30 = 475 minutes net
• 475 minutes = 7 hours, 55 minutes remainder
• Net working time: 7h 55m

You can check any of these instantly with the Break Calculator, which also works for 30-, 45-, and 60-minute lunches without any extra setup.

More than one break in a shift

Some shifts have more than a single lunch break — a short morning break, a lunch, and a short afternoon break, for example. The formula still works the same way; just add every break's length together before subtracting the total from the gross shift time. A shift with a 10-minute morning break, a 30-minute lunch, and a 10-minute afternoon break has 50 minutes of total break time to subtract, not just the 30-minute lunch. If a day is really split into separate blocks of work rather than one shift with breaks in the middle, the Work Hours Calculator is often a cleaner fit, since it totals each work period directly instead of subtracting break time from one long shift.

Rounding to the nearest quarter hour

Some employers round clock-in and clock-out times to the nearest 5, 6, or 15 minutes for payroll simplicity, as long as the rounding evens out over time and doesn't consistently shortchange employees. If your workplace rounds, apply the rounding to the clock times first, then subtract the break — rounding after subtracting the break can give a slightly different (and sometimes less accurate) result.

Common mistakes

• Subtracting minutes from an hours-and-minutes figure directly. "8 hours 15 minutes minus 30 minutes" isn't "8 hours minus 15 minutes" — convert everything to minutes first to avoid borrowing errors.
• Forgetting the break entirely on a long shift. A shift that looks like "8 hours" on the clock might really be 7.5 hours worked once the break comes out.
• Assuming the break is always paid or always unpaid. Short breaks (5 to 20 minutes) are generally treated as paid working time under federal law, while longer, bona fide meal periods are generally unpaid. See our guide on whether lunch breaks are paid for the details.
• Only subtracting one break when there were several. Add up every break in the shift before subtracting, not just the longest one.

Estimates only. Not legal, tax, or payroll advice.