Work Hours Calculator

Enter a shift the way it reads on the clock — start hour and minute, end hour and minute, all on the 24-hour clock — along with the unpaid break in minutes, and the calculator returns the paid length of that shift in hours and minutes, the same figure as payroll-ready decimal hours, and the weekly total for however many days you work. Add an hourly rate and it prices the week as well. The decimal figure is the one to lift onto a timesheet: 8 h 0 min is entered as 8.00 and 7 h 30 min as 7.50, because payroll software multiplies hours against rates and needs the minutes expressed as a fraction of an hour.

How the paid time is worked out

Both clock times are converted to minutes since midnight and subtracted:

shift = (endh × 60 + endm) − (starth × 60 + startm)

When that figure is negative the finish belongs to the next day, so 1,440 minutes are added. This matches the time duration calculator on this site and fires only when the end is strictly earlier than the start. A start and end that are identical therefore produce a zero-length shift, which is reported as an error rather than silently read as 24 hours — a genuine round-the-clock stint should be entered as two shifts. The unpaid break comes off next, and the remainder becomes decimal hours:

paid hours = (shift − break) ÷ 60

The weekly figure multiplies paid hours by days per week, and the pay figure multiplies the weekly hours by the hourly rate when one is supplied; leave the rate blank and the pay row simply stays empty. A break as long as the whole shift leaves nothing to pay and is also flagged as an error, since a zero-hour timesheet line is nearly always a typo.

Two worked shifts

The default inputs describe a common office pattern: 9:00 to 17:30 with half an hour of unpaid lunch. The start is 9 × 60 = 540 minutes into the day and the end is 17 × 60 + 30 = 1,050, so the clock time spans 1,050 − 540 = 510 minutes. Removing the 30-minute break leaves 480 minutes, which is 480 ÷ 60 = 8.00 decimal hours, shown as 8 h 0 min. Five of those shifts total 40.00 hours for the week, and at a rate of 20.00 the week is worth 800.00.

A night shift exercises the rollover rule. Clocking in at 22:00 and out at 06:00 gives 360 − 1,320 = −960 minutes; adding the 1,440-minute day brings it to 480 minutes of clock time. The same 30-minute break cuts that to 450 minutes, which is 7 h 30 min, or 7.50 decimal hours. Across five nights that makes 37.50 hours, and at the same 20.00 rate the week pays 750.00 — two and a half hours short of the day worker's total, because the night shift spans eight clock hours where the day shift spans eight and a half. The arithmetic never notices midnight; only the rollover step does.

The key that invented clocking in

Before a shift could be paid to the minute it had to be recorded to the minute, and the machine that made such records routine came out of a jeweler's shop in Auburn, New York. Willard L. Bundy filed for a patent on his Time-Recorder on 3 August 1887 and was granted US patent 393,205 on 20 November 1888. The filing is blunt about what the machine was for: "to compel employes of factories and shops to record at their place of business the time of their entering", and so save "the extra expense of watchmen or time-keepers usually employed for the aforesaid purpose". The mechanism gave every employee a key with a uniquely shaped lug; turning it in the machine rotated a set of wheels to that worker's identification number and pressed a spring-loaded platen against a paper strip, printing the number and the hour side by side.

Bundy's younger brother Harlow saw the business in it, and in 1889 the two organized the Bundy Manufacturing Company in Binghamton, New York, the first firm in the world built to manufacture time clocks; a WSKG history of the brothers puts the works at around 135 skilled workers. In 1900, at the urging of the director George W. Fairchild, the time-recording side of the business was folded into the newly formed International Time Recording Company, which moved to nearby Endicott in 1907. On 16 June 1911 the financier Charles Ranlett Flint bundled ITR, Bundy Manufacturing and two other measurement businesses — the Tabulating Machine Company and the Computing Scale Company of America — into the Computing-Tabulating-Recording Company, based in Endicott. In February 1924, under Thomas J. Watson, CTR took the name it still carries, International Business Machines, and IBM stayed in the time-clock trade for decades more, selling its Time Equipment Division to the Simplex Time Recorder Company in 1958. The punch clock, in other words, was an information machine, counting minutes half a century before its corporate descendants counted anything else.

Decimal hours, the payroll dialect

Payroll runs on decimal hours because pay is a multiplication, and multiplying a rate by 7 hours 45 minutes requires converting the minutes anyway. The conversion is minutes ÷ 60: 15 minutes is 0.25, 20 minutes is 0.33, 30 is exactly 0.50 and 45 is 0.75, so 7 h 45 min is entered as 7.75. The trap is reading the decimal point as a clock. A timesheet entry of 7.45 is not 7 hours 45 minutes but 7 hours and 0.45 × 60 = 27 minutes, a difference of 18 minutes that compounds across a pay period. This calculator does the conversion from the raw minute count and rounds to two decimal places only at display time, so the weekly figure is the daily figure multiplied through at full precision rather than a rounded number multiplied again.

Which breaks are unpaid

The calculator subtracts whatever break you give it, but the law is particular about which breaks an employer may treat as unpaid. In the United States, the Department of Labor's regulations under the Fair Labor Standards Act draw the line by length and by freedom. Short rest breaks — the regulation at 29 CFR 785.18 speaks of spells running from 5 minutes to about 20 — must be counted as hours worked. A bona fide meal period is different: under 29 CFR 785.19 it is not working time, ordinarily needs to run 30 minutes or more, and requires the employee to be completely relieved from duty, so an office worker required to eat at the desk is working while eating. The employer does not, however, have to let staff leave the premises for the period to count as a genuine break. What federal law never does is require the breaks in the first place: the Department of Labor's position is that the FLSA does not oblige employers to provide meal or rest periods at all, though many states do. Timesheet rounding is regulated as well — 29 CFR 785.48(b) accepts times recorded to the nearest 5 minutes, one-tenth or one-quarter of an hour, provided the practice does not, over time, fail to compensate employees for all the time they have actually worked, so rounding that only ever falls in the employer's favor does not qualify. Rules elsewhere differ by jurisdiction and by contract, so treat the break field as a statement of fact about your pay arrangement, not a legal judgment: enter the minutes your employer actually deducts.

Assumptions and conventions

The calculator models one repeating shift: the weekly figures assume every working day uses the same times and the same break, and a rota with mixed shifts needs one calculation per shift pattern. The break is a single daily total of unpaid minutes, capped at 240, and paid rest breaks should not be entered, since they belong inside the paid time. Days per week accepts half-day steps between 1 and 7, so a five-and-a-half-day week is expressible. A single shift is always read as shorter than 24 hours, with 23 h 59 min the longest span the inputs can describe. Pay is gross and flat: the weekly amount is hours times rate with no overtime premium, night differential, penalty rates or tax, and the rate field accepts values up to 100,000. The overtime omission matters past 40 hours, because 29 U.S.C. 207(a)(1) entitles covered US workers to at least one and one-half times the regular rate for hours beyond 40 in a workweek — a 45-hour week at 20.00 is federally worth 950.00, not the 900.00 the flat multiplication returns. Displayed hours are rounded to two decimal places while internal arithmetic keeps full precision, so a figure that reads 7.83 may carry hidden fractions into the pay result rather than exactly 7.83 × rate.

Frequently asked questions

How do I calculate hours worked for a timesheet?

Convert both times to minutes since midnight, subtract the start from the end, then take off any unpaid break and divide by 60. A 9:00 start and a 17:30 finish span 510 minutes; removing a 30-minute lunch leaves 480 minutes, which goes on the timesheet as exactly 8.00 hours.

Are lunch breaks included in hours worked?

Under the US Department of Labor regulation at 29 CFR 785.19, a bona fide meal period is not working time. It ordinarily needs to run 30 minutes or more and the employee must be completely relieved from duty, so eating at a desk while covering the phones still counts as work. Short rest breaks are treated differently: 29 CFR 785.18 says spells of 5 to about 20 minutes must be counted as hours worked.

How do I convert minutes to decimal hours for payroll?

Divide the minutes by 60. So 45 minutes is 0.75 hours, and a shift of 7 hours 45 minutes goes on the timesheet as 7.75, not 7.45. To go the other way, multiply the decimal part by 60 to recover the minutes.

How are overnight shift hours calculated?

Enter the times as they read on the clock and let the finish fall before the start. The calculator adds 24 hours whenever the end time is earlier, so a 22:00 to 06:00 shift counts 8 clock hours, and with a 30-minute unpaid break it pays 7.50 hours.

Who invented the punch clock?

Willard L. Bundy, a jeweler in Auburn, New York, was granted US patent 393,205 for his key-operated time recorder on 20 November 1888. With his brother Harlow he founded the Bundy Manufacturing Company in Binghamton in 1889; the business was folded into the Computing-Tabulating-Recording Company in 1911, and that firm was renamed International Business Machines in February 1924.

Is 9 to 5:30 with a half hour lunch a 40 hour week?

Yes. The clock time from 9:00 to 17:30 is eight and a half hours; removing the 30-minute unpaid lunch leaves 8.00 paid hours a day, and five of those shifts make exactly 40.00 hours. That lands precisely on the US federal overtime threshold: under 29 U.S.C. 207(a)(1), hours beyond 40 in a workweek must be paid at no less than one and one-half times the regular rate.