Hours Calculator

What the span between two times means

The calculator measures from your start time to your end time on the clock face and hands back the same span four ways: hours and minutes, decimal hours, total minutes and, if you enter a rate, gross pay. A day that runs from 9:00 a.m. to 5:00 p.m. covers 480 minutes, and 480 / 60 = 8 hours.

When the end time falls earlier than the start time, the span crosses midnight, so the tool adds a full day before doing the math. A shift from 10:15 p.m. to 6:45 a.m. has 105 minutes left before midnight and 405 minutes after it, and 105 + 405 = 510 minutes, which is 8 hours 30 minutes. You never have to type a date or press a separate overnight button.

The break box exists because a lunch hour is usually not paid. If your break is paid, leave the box at zero. If you want battery life in hours instead of clock hours, that is a different question with its own page: the mAh to hours calculator Time zones belong to the time difference calculator.

Worked example: nine to five with a lunch break

A standard office day runs 9:00 a.m. to 5:00 p.m., which is 480 minutes of clock time. Take the unpaid 30 minute lunch out and 480 - 30 = 450 minutes, which the payroll system writes as 7.50 decimal hours. At $22 an hour the day pays 7.5 x 22 = 165 dollars.

• Span between the two times: 8 h 00 min.
• Paid time after the lunch: 7 h 30 min.
• Decimal hours: 7.50.
• Gross pay for the day at $22: $165.
• Gross pay for a five day week: 7.5 x 5 = 37.5 paid hours, and 37.5 x 22 = $825.

Thirty-seven and a half paid hours sits under the 40 hour line where federal overtime starts, which is why a plain nine to five week rarely shows overtime on the paycheck. For the full time card picture, with rounding rules and weekly totals, the hours worked calculator runs the same math one step further.

Worked example: the night shift

A night shift that starts at 10:15 p.m. and ends at 6:45 a.m. crosses midnight. The clock face looks like it went backwards, but the span is real: 105 minutes before midnight plus 405 minutes after it, 510 minutes in total, and after a 30 minute meal break it leaves 480 minutes, exactly 8 hours of paid work.

Odd minutes work the same way. A shift from 7:42 a.m. to 4:18 p.m. spans 516 minutes. With a 45 minute unpaid lunch, 516 - 45 = 471 minutes, which is 7 h 51 min. In decimal that is 471 / 60 = 7.85 hours, and at $22 an hour the day pays 7.85 x 22 = 172.70 dollars before tax.

For shifts that stretch across several days, enter the dates too: the time duration calculator measures from one date and time to another and reports whole days as well as hours.

Decimal hours: the format payroll uses

Payroll systems do not store 7:30. They store 7.50, because decimal hours let one multiplication do the pay. The conversion is minutes divided by 60, and it only ever touches the minutes after the hour.

Two of these rows show up everywhere: 15 minutes is 0.25 and 30 minutes is 0.50, so a quarter hour costs 0.25 and half an hour costs 0.50 of an hour. Going the other way, 36 minutes is 36 / 60 = 0.60, which is why 8 h 36 min shows up on payroll as 8.60 decimal hours.

The classic mistake is reading 7.30 in a payroll report as seven hours thirty minutes. It is not. The decimal 0.30 is 0.30 x 60 = 18 minutes, so 7.30 stands for 7 h 18 min. The calculator shows both formats side by side so you can check one against the other before the timesheet goes in.

Which breaks come out of your hours

Under federal rules the break box should only hold an unpaid meal period. The Department of Labor draws the line at purpose and length: short rest breaks of about 5 to 20 minutes are counted as paid working time, while a bona fide meal period, typically 30 minutes or more where you are fully relieved from duty, does not have to be paid. Those rules come from 29 CFR 785.18 and 29 CFR 785.19, summarized on the DOL breaks and meal periods page.

In practice:

• Paid, do not subtract: a 15 minute coffee break, a 10 minute stretch break, smoking breaks.
• Unpaid, subtract: a 30 minute lunch where you can leave the desk, an hour dinner break on a long shift.
• Gray zone: eating at your desk while answering the phone is working time, not a meal period, because you are not relieved from duty.

State law can require more generous breaks than federal law, and where both apply the employee gets the better deal. If you are rebuilding a time card rather than planning a day, the hours worked calculator adds the rounding rules employers use on top of the same math.

Adding hours onto a time

The second mode answers the question in the other direction: not how long, but until when. A medication schedule that doses every 8 hours starting at 10:00 p.m. wants the next time, not a duration. The math runs on minutes after midnight. 9:15 p.m. is 1,275 minutes in; 8 hours 45 minutes adds 525 more, and 1,275 + 525 = 1,800 minutes. That is past midnight, so take 1,800 - 1,440 = 360 minutes, which reads as 6:00 a.m. the next day. The calculator does the day rollover on its own and tells you which day the answer lands on.

A daytime example: a bread dough that proofs 6 hours 20 minutes from a 7:40 a.m. start finishes at 2:00 p.m., because 460 + 380 = 840 minutes, and 840 / 60 = 14, which is 2:00 p.m. on the 12 hour clock. If you are adding several spans together, say 1 h 45 min plus 2 h 15 min plus 50 min, use the time calculator, which sums spans and converts to decimal in one pass.

Hours, overtime and the 40 hour week

The number 40 is the hinge of United States wage law. The Fair Labor Standards Act requires overtime pay at one and a half times the regular rate for every hour worked above 40 in a workweek, where a workweek is a fixed, recurring stretch of 168 hours, seven days back to back. The Department of Labor lays this out on its overtime page.

How much is a full time week in practice? On days they worked, full time employed people put in an average of 8.1 hours in 2025, and 8.5 hours on an average weekday, according to the Bureau of Labor Statistics American Time Use Survey. Five 8.5 hour days is 8.5 x 5 = 42.5 hours, which crosses the overtime line by 2.5 hours. At a $22 base rate the overtime rate is 22 x 1.5 = 33 dollars an hour, and those 2.5 hours are worth 2.5 x 33 = 82.50 dollars extra.

Some states add daily overtime on top of the weekly rule. California, for one, pays overtime after 8 hours in a day, and the California overtime calculator runs those rules. Checking where your own week sits before you agree to extra shifts is the whole point of counting hours: the span is easy, the pay rules on top of it are where the money hides.

Mistakes that make hours come out wrong

• Reading 7.30 as seven thirty. In payroll 7.30 is 7 h 18 min, because 0.30 x 60 = 18 minutes. Seven and a half hours is 7.50.
• Subtracting paid breaks. A 15 minute rest break is paid time under federal rules. Taking it out understates hours, and doing it every day of a pay period adds up to real money.
• Double cutting the lunch. If the time clock already excludes the lunch, entering the break again removes it twice.
• Forgetting the midnight flip. 10:15 p.m. to 6:45 a.m. is 8 h 30 min, not a negative number. If a spreadsheet gives a minus, add 1,440 minutes.
• Mixing up noon and midnight. 12:00 a.m. is the start of the day, midnight. 12:00 p.m. is noon. An 8 hour shift from midnight ends at 8:00 a.m.
• Rounding by hand. 7:26 is 7.43 decimal hours, not 7.5. Let the calculator carry the minutes.

When the numbers come out strange, pull the total minutes line and check it against the times by hand: minutes from midnight for the end, minus minutes from midnight for the start, plus 1,440 if the end is smaller. That is the whole algorithm the calculator runs, and it fits on a receipt.