How many hours is 8:45 to 5:00 with a 45-minute lunch?

7.5 hours. The span from 08:45 to 17:00 is 8 hours 15 minutes (8.25 hours), and deducting the 0.75-hour lunch leaves 7.50 paid hours.

Why doesn't 7:30 plus 8:15 equal 15.45 hours?

Because clock times are not decimals. 7 hours 30 minutes plus 8 hours 15 minutes is 15 hours 45 minutes, which converts to 15.75 decimal hours — adding the columns as if minutes were hundredths understates the total.

Do unpaid lunch breaks count toward overtime?

No. Unpaid breaks are subtracted before hours are totaled, so they do not count toward the 40-hour federal overtime threshold — only paid working time does.

Is it legal for my employer to round my punches?

Generally yes, to the nearest quarter hour, under 29 CFR 785.48 — but the rounding must be neutral in practice. A policy that always rounds in the employer's favor does not comply.

Guides

How do I add up work hours from clock-in and clock-out times?

By TimeLab · Published June 10, 2026 · Updated June 10, 2026

Convert each shift to decimal hours — clock-out minus clock-in minus the unpaid break — and add the shifts together: the worked five-shift week below totals exactly 39.08 hours, or $742.52 gross at $19 per hour.

The three-step method for one shift

Every shift reduces to the same three steps: subtract the clock-in from the clock-out, deduct any unpaid break, and convert the result to decimal hours. Take a Monday that runs 08:00 to 16:30 with a 30-minute unpaid lunch. The elapsed span is 8 hours 30 minutes; removing the lunch leaves 8 hours 0 minutes; in decimal form that is 8.00 paid hours.

The reliable way to do this by hand is to work in minutes, exactly as the TimeLab engine does. A 16:30 clock-out is 990 minutes after midnight and an 08:00 clock-in is 480, so the span is 990 − 480 = 510 minutes; subtracting the 30-minute break leaves 480 minutes; dividing by 60 gives 8.00 hours. Working in minutes sidesteps the borrow-and- carry mistakes that creep in when you subtract clock times directly.

Converting minutes to decimal hours

Payroll and invoicing multiply hours by a rate, so the hours must be decimal. The classic trap is treating the minutes column as decimals: 7 hours 30 minutes is 7.5 hours, not 7.3. The quarter-hour anchors are worth memorizing — 15 minutes is 0.25, 30 minutes is 0.50, and 45 minutes is 0.75 of an hour.

For everything in between, each minute is 1/60 of an hour, about 0.0167: 6 minutes is exactly 0.1 hours, 12 minutes is 0.2, and 50 minutes is 0.8333, which rounds to 0.83. That last one shows up in the worked week below: a Friday shift of 08:00 to 16:50 with a 30-minute break is 500 paid minutes, which the engine reports as 8.33 hours.

A full worked week, added up

Here is a five-shift week with an unpaid lunch every day, run through the TimeLab weekly time card engine. Monday 08:00–16:30 with a 30-minute lunch is 8.00 hours; Tuesday 08:45–17:00 with a 45-minute lunch is 7.50; Wednesday 09:15–17:30 with a 30-minute lunch is 7.75; Thursday 07:30–16:00 with a 60-minute lunch is 7.50; Friday 08:00–16:50 with a 30-minute lunch is 8.33. The shifts sum to exactly 39.08 hours for the week.

At $19 an hour, 39.08 hours is $742.52 of gross pay. Because the week stays under 40 hours there is no overtime band — every hour is priced at straight time. Had the total crossed 40, the hours past the threshold would be priced at 1.5 times the rate; the calculator performs that split automatically, and gross pay is before taxes and deductions in either case.

Overnight shifts and unpaid breaks

A clock-out that is earlier than the clock-in means the shift crossed midnight, and the engine handles it by adding 24 hours to the end time. A 23:00 clock-in with a 07:30 clock-out is an 8.5-hour span, and after a 30-minute unpaid break it counts as exactly 8.00 paid hours — not a negative number. The one limit of this convention is that a single entry cannot represent a span of 24 hours or more; split such a stretch into two entries.

Only unpaid breaks should be entered in the break field, because they are subtracted from paid time. Under the Department of Labor's hours-worked rules, short rest breaks of roughly 5 to 20 minutes are customarily counted as paid work time, while a bona fide meal period — typically 30 minutes or more, with the worker fully relieved of duty — may be unpaid. A lunch you work through is not a bona fide meal period and should not be deducted.

Rounding and the 7-minute rule

Many employers do not pay on raw punches: federal regulation 29 CFR 785.48 permits rounding punch times to the nearest quarter hour, as long as the practice is neutral and does not systematically underpay over time. The "7-minute rule" is the folk name for how nearest- quarter rounding behaves: punches 1 to 7 minutes past a quarter mark round down, and punches 8 to 14 minutes past round up — an 8:07 clock-in becomes 8:00, while an 8:08 clock-in becomes 8:15.

The calculator takes the opposite approach: it uses the exact minutes you enter and only rounds the displayed result to two decimal places. That makes it a useful cross-check on a rounded paystub — total your actual punches here, compare against the rounded total you were paid for, and you can see in minutes whether a rounding policy is washing out evenly or consistently cutting against you.

Questions

How many hours is 8:45 to 5:00 with a 45-minute lunch?: 7.5 hours. The span from 08:45 to 17:00 is 8 hours 15 minutes (8.25 hours), and deducting the 0.75-hour lunch leaves 7.50 paid hours.
Why doesn't 7:30 plus 8:15 equal 15.45 hours?: Because clock times are not decimals. 7 hours 30 minutes plus 8 hours 15 minutes is 15 hours 45 minutes, which converts to 15.75 decimal hours — adding the columns as if minutes were hundredths understates the total.
Do unpaid lunch breaks count toward overtime?: No. Unpaid breaks are subtracted before hours are totaled, so they do not count toward the 40-hour federal overtime threshold — only paid working time does.
Is it legal for my employer to round my punches?: Generally yes, to the nearest quarter hour, under 29 CFR 785.48 — but the rounding must be neutral in practice. A policy that always rounds in the employer's favor does not comply.