Calculating hours for overnight shifts

Guide · last reviewed 1 November 2026 · Hours Calculator Online

Night work breaks the one piece of arithmetic everybody trusts. On a day shift, end minus start always gives a sensible answer. Cross midnight and the same subtraction tells you that you worked negative sixteen hours. Spreadsheets return ########, hand-written sheets get a guess written in the total column, and the guess is usually wrong by a quarter of an hour.

The fix is a single rule, and once you see why it works you will never mis-total a night shift again. Below: the rule, three worked examples, how to decide which calendar day the shift belongs to, what happens on the two daylight-saving nights a year, and how to put the whole thing on a timesheet so payroll does not query it.

Why end minus start goes negative

Clock time is a 24-hour loop, not a number line. Midnight resets the count to zero. So when your shift starts at 22:00 and ends at 06:00, the end value is numerically smaller than the start value even though more time has passed.

Converted to minutes past midnight the problem is plain:

That gap is not a coincidence. The end time belongs to the next day, so its true position on a continuous timeline is 360 + 1440 = 1800 minutes from the start of the first day. Subtract properly and 1800 − 1320 = 480 minutes. Eight hours, which is what the clock on the wall would have told you.

The add-24-hours rule

Written as a procedure you can run on paper:

1. Convert both times to minutes past midnight.
2. If the end value is less than or equal to the start value, add 1440 to the end value.
3. Subtract: end − start gives elapsed minutes.
4. Subtract the unpaid break in minutes.
5. Divide by 60 for hours and minutes, or by 60 as a decimal for payroll.

Every calculator on this site implements exactly that rule. When the end time is earlier than the start, the shift is treated as crossing midnight by adding 24 hours, with no checkbox to tick and nothing to configure. The whole computation stays in whole minutes, so there is no floating-point drift; decimal hours are produced only at the end, rounded to two decimals. And if you enter a break longer than the shift, you get an explicit error instead of a negative total. The time duration calculator is the quickest way to check a single overnight span; the hours calculator adds the break and an optional pay rate.

Worked example: 10:00 PM to 6:00 AM

A warehouse night shift with a 30-minute unpaid meal period.

Nothing subtle here, but note the discipline: the break comes off after the span is resolved, never before. Mixing the order on a split meal period is where people lose minutes.

Worked example: 11:30 PM to 7:15 AM with a break

A hospital support shift with a 45-minute unpaid meal period.

The decimal conversion is where this one usually goes wrong. Before the break the span is 7:45, which is 7.75 decimal hours — not 7.45. If somebody writes 7.45 on the sheet and then deducts 0.45 for the break, they end up at 7.00 by coincidence and never notice the two errors cancelled. Next week, with a 30-minute break, they will be out by 18 minutes. Convert minutes to decimal hours explains the division, and the hours to decimal converter does it both ways.

Worked example: a long night with a split break

Security cover, 7:45 PM to 8:00 AM, with two unpaid 20-minute meal breaks and a paid 15-minute rest break.

Short rest breaks are generally treated as compensable hours worked, which is why the 15 minutes stays in the total. A bona fide meal period of 30 minutes or more during which the employee is completely relieved of duty generally is not compensable — but these two were 20 minutes each, so under the general federal principle they would normally count as worked time. State rules on meal and rest breaks vary widely, and some states mandate paid rest periods and unpaid meal periods of specific lengths, so check your state labor agency or your employer's policy before assuming. The reasoning is unpacked in lunch breaks: paid or unpaid?.

Which calendar day does the shift belong to?

The arithmetic gives you 450 minutes. It does not tell you whether those minutes are Tuesday's or Wednesday's, and that choice matters in three places.

The common convention is to assign the entire shift to the calendar day on which it started. It keeps one shift on one timesheet line, keeps the daily total equal to the shift length, and makes auditing straightforward. The alternative — splitting the hours at midnight — is sometimes required where a daily premium or a differential window depends on the actual clock hours.

Pick one and never mix them inside a pay period. Mixing is how a night shift gets counted in two weeks at once, or in neither.

The Sunday-to-Monday boundary

Under the FLSA the workweek is a fixed, recurring 168-hour period chosen by the employer — commonly Sunday 12:00 AM through Saturday 11:59 PM, but it can start on any day and at any hour. A Sunday-night shift that runs into Monday morning straddles that boundary, and the consequence is real money.

Five and a half overtime hours appear or vanish depending on a convention nobody wrote down. If you work nights near your workweek boundary, find out in writing when your workweek starts and which method your employer uses. The overtime calculator lets you test both arrangements in a minute, and overtime rules explained covers the 40-hour rule and the regular rate in detail. Remember that the FLSA sets no federal daily overtime requirement, though some states do impose one.

Daylight saving: the 7-hour and 9-hour nights

Twice a year, in jurisdictions that observe daylight saving time, one night is not 24 hours long. In the spring the clocks jump forward and a scheduled eight-hour overnight shift elapses in seven actual hours; in the autumn they fall back and the same shift takes nine.

The general principle for non-exempt employees is that you are paid for hours actually worked, so the autumn night is nine hours on the clock and the spring night is seven. Plain clock subtraction cannot see this, because it has no idea the local offset changed — and that includes every calculator on this site, which works in local wall-clock minutes by design. On those two nights, adjust the total by hand or log the shift as two lines around the transition, and make a note on the timesheet explaining why the figure differs from the roster.

Shift differentials in general terms

A shift differential is extra pay for working less desirable hours: a flat amount per hour, a percentage uplift, or a fixed sum per shift. It is a contractual or policy matter rather than a federal requirement — there is no general federal rule obliging an employer to pay more for night work.

Where a differential does exist, two mechanical points matter. First, a non-discretionary differential generally has to be included in the regular rate used to compute overtime, which means your overtime premium is calculated on a slightly higher base than your nominal hourly rate. Second, differentials usually attach to a window — say 6:00 PM to 6:00 AM — so you need to know how many of your hours fell inside that window, which is precisely the split-at-midnight breakdown from earlier.

Rates, windows and eligibility differ from employer to employer, so treat the structure above as the shape of the calculation, not as your entitlement. Your handbook or collective agreement is the authority.

Recording a night shift on a timesheet

Put the shift on one line, dated by its start day, with both clock times and an AM/PM marker or 24-hour notation that cannot be misread. 22:00 and 06:00 remove all doubt; 10:00 and 6:00 with no marker will be read wrongly by somebody eventually.

• Flag the crossing. A short note — "out 6:00 AM Wed" — stops a reviewer from treating the line as a daytime shift and querying a negative total.
• Record meal periods with actual start and end times, not just a minute count. If a night meal gets interrupted by a call-out, you want the record to show it.
• Keep the per-day total equal to the shift length if you use the shift-start convention, and add a second line only when the split-at-midnight method is required.
• Note daylight-saving nights explicitly, because a 9:00 total against an 8:00 roster will otherwise look like an error.

The time card calculator and the timesheet calculator both handle overnight rows automatically and keep the week in your own browser via localStorage, never uploading it. For the broader mechanics of a weekly sheet — cost codes, travel time, paid leave lines, approvals — see how to fill out a timesheet. If you want to add a duration to a clock time rather than subtract two times, the add time calculator does that, and the work time calculator covers the common payroll cases in one place.

Quick reference

Check any row by hand: convert both times to minutes past midnight, add 1440 to the smaller end value, subtract, then take off the break. The arithmetic is dull, which is the point — a dull rule applied the same way every night is what keeps a night-shift paycheck correct.

This is general guidance on time arithmetic and recordkeeping, not legal or payroll advice. Overtime thresholds, break requirements, differentials and daylight-saving handling differ by state and by country; your employer's policy and your state labor agency are the authorities for your own situation.

Last reviewed 1 November 2026. Corrections welcome at our contact page.