In-depth guide · Hours
How to Calculate Hours Worked on a Time Card
How to calculate hours worked from in and out punches: subtract, remove unpaid meal breaks, handle overnight and DST shifts, convert to decimal.
Updated · 11 min read
Time cards & hours · calculator
Hours calculator
The hours and minutes between two times, minus an unpaid break — across midnight, and right on the two nights a year the clocks change.
Your shift
Example/ hour
Like 19.50 or $19/hr. Straight time only — no overtime is added here.
Try an example
Hours worked
12:0012.00 hours
12 hours
7:00 PM to 7:30 AM the next day: 12:30 by the clock, minus a 0:30 unpaid break = 12:00 (12.00 hours).
Ends the next day. A shift is counted on the day it starts.
Worked on a night the clocks changed? Add the date and it will be counted.
Worked 12:00, 12.00 hours.
RuleHours worked = end − start − unpaid break; a shift that ends at or before its start time ends the next day; U.S. clocks go forward at 2:00 AM on the second Sunday of March and back at 2:00 AM on the first Sunday of NovemberSources checked How the math works ↓
The shift on a 24-hour dial
Scale: 1 hour = 15° of the dial · midnight at the top
How to read it
The ring is one day: midnight at the top, noon at the bottom, one hour every 15°. The dark arc is the time between the punches; it runs past midnight, so the shift ends the next day.
On the two nights a year the clocks change, add the date: the dial then shows the hour gained or lost.
Calculated with Punch Clock Math · rules checked October 22, 2026 · an estimate, not legal or tax advice · punchclockmath.com
How the math works
Every time is turned into whole minutes after midnight; nothing is rounded until the very end.
- Read the times7:00 PM = 1,140 minutes after midnight; 7:30 AM = 450.A time typed without AM or PM is read as the one soonest after the start (8:00 then 4:30 reads 4:30 PM); the field shows its reading and lets you flip it.
- Cross midnightEnd at or before start → the shift ends the next day: 450 + 1,440 − 1,140 = 750 minutes (12:30).Start and end exactly the same is counted as no time, and flagged — never as 24 hours.
- Daylight saving time (with a date)U.S. clocks go forward at 2:00 AM on the second Sunday of March and back at 2:00 AM on the first Sunday of November. A shift that covers the spring change is 60 minutes shorter than its clock times; one that covers the fall change is 60 minutes longer.Only if your clock changes. The U.S. Department of Transportation: “Daylight Saving Time is not observed in Hawaii, American Samoa, Guam, Northern Mariana Islands, Puerto Rico, the Virgin Islands, and most of Arizona.”15 U.S.C. 260a — Advancement of time or changeover dates · Daylight Saving Time
- Take off the unpaid break750 − 30 = 720 minutes.Short rest breaks of about 5 to 20 minutes are hours worked and must be paid. They cannot be offset against other time. Bona fide meal periods (ordinarily 30+ minutes, completely relieved from duty) are not work time. Enter only the break that is unpaid.29 CFR 785.18 · 29 CFR 785.19
- Convert once720 ÷ 60 = 12:00 = 12.00 hours.Decimal hours are rounded half up to the hundredth, once, at display. Several shifts are added in minutes first, then converted.
- Pay (if you add a rate)rate × minutes ÷ 60, rounded to the cent once.Straight time only. For overtime use the time card or overtime calculator.
What this doesn’t cover
- Overtime: this adds hours only. Overtime depends on the whole workweek and your state’s rules — the time card calculator applies them.
- Rounding of punches: times are counted to the minute. To see what 5-, 6- or 15-minute rounding does, use the time clock rounding calculator.
- Which breaks are paid: you decide what to enter as unpaid. State meal- and rest-break rules are on the break laws by state page.
- Time zones and travel: both times are read on the same local clock. A shift that crosses time zones is not modeled.
- Seconds: time cards record minutes; seconds are not modeled.
Guides that explain this tool
Guide · Hours
Daylight Saving Time and Night Shifts: 7 Hours or 9?
On a daylight saving night, a 10 PM to 6:30 AM shift is 9 hours in November and 7 in March. The 2026 and 2027 dates, the pay rule and the time card entry.
Updated · 5 min read
Guide · Rules
Are Breaks Paid? Rest Breaks, Meal Periods and State Rules
Federal law requires no breaks, but short breaks are paid and true meal periods are not. States requiring meal or rest breaks, and auto-deducted lunches.
Updated · 6 min read
Page sources
Every rule above comes from these pages, read on the dates shown.