Updated July 18, 2026
Tracking work hours accurately keeps pay correct and scheduling sane. This guide covers the timekeeping conversions that come up most and the tool for each.
Hours and durations
The foundation of any timesheet is the time between clock-in and clock-out. The Time Duration Calculator returns hours and minutes between two times, including overnight shifts, while the Add or Subtract Time Calculator adds or subtracts hours and minutes from a starting time and flags when the result rolls into another day.
Decimal hours for payroll
Payroll systems multiply a pay rate by decimal hours, not hours and minutes, so 7 hours 30 minutes becomes 7.50. Getting this conversion right prevents under- and over-payment. The Decimal Hours Calculator converts H:MM to decimal and back; remember the common marks: 15 minutes is 0.25, 30 is 0.50, 45 is 0.75.
Military (24-hour) time
24-hour time removes the AM/PM ambiguity that causes scheduling mistakes - 1300 is unmistakably 1:00 PM. It's standard in healthcare, aviation, the military and many timesheets. The Military Time Converter converts between 24-hour and 12-hour formats in both directions.
Time zones
Coordinating across locations means converting time zones, and daylight saving makes it tricky because the offset changes through the year. The Time Zone Converter converts a date and time between major world zones and handles daylight-saving automatically, so a 9 AM call in New York shows correctly for a colleague in London or Tokyo.
Accuracy tips
Two habits prevent most timesheet errors: convert to decimal hours before applying a pay rate, and double-check overnight or cross-zone entries where the date can change. For recurring schedules, settle on one format (usually 24-hour) to remove ambiguity, and round consistently according to your employer's policy.
One shift, four conversions
A single shift usually has to pass through every conversion on this page before it reaches a paycheck. Take a shift logged as 9:00 AM to 4:45 PM with a 30-minute lunch. Written in 24-hour time, that is 09:00 to 16:45, which removes any AM/PM ambiguity before you do the subtraction. The raw duration is 7 hours 45 minutes; subtract the 30-minute lunch and you get 7 hours 15 minutes worked. Converting the 15 leftover minutes to a decimal (15 / 60 = 0.25) turns that into 7.25 hours, the figure a payroll system actually multiplies by an hourly rate. If the same employee needs to confirm a scheduling call with a colleague three time zones east, the 16:45 clock-out converts through UTC and lands at a different local hour depending on whether either zone is currently observing daylight saving, which is exactly why the time zone tool checks the date, not just the offset.
Rounding, the step nobody mentions until a paycheck is short
Everything above assumes the punches themselves are exact. Often they aren't, and lawfully so. Under 29 CFR 785.48(b), an employer may record time to the nearest 5 minutes, tenth of an hour, or quarter hour, so long as the rounding averages out instead of consistently trimming pay. Quarter-hour rounding produces the famous 7-minute boundary: a 7:52 AM arrival becomes 7:45 on the record, while 7:53 becomes 8:00. Knowing which system your employer uses turns a confusing pay stub into a checkable one. Convert your own unrounded punches with the tools on this page, compare against the official total, and expect small differences that wander in both directions. What you should not see is a discrepancy that always favors the same side; the regulation conditions the whole practice on it evening out over time.
Auditing one pay period, in order
The workflow that catches errors fastest runs the conversions in a fixed sequence rather than ad hoc. First put every punch into 24-hour form so AM/PM mistakes die early. Second, total each day in minutes, subtracting only unpaid breaks. Third, convert daily totals to decimal hours and sum the week. Only then compare against the stub. Done in that order, a discrepancy points at one specific step; done all at once in your head, a discrepancy points everywhere.
All calculators on this site
- Time Calculator - Hours worked between a start and end time, minus breaks.
- Hours Calculator - Add up daily hours into a weekly total with pay.
- Time Card Calculator - A full week of clock-in/out times with daily and weekly totals.
- Overtime Calculator - Overtime pay at 1.5× or 2× your regular rate.
- Date Calculator - Days between dates, or add and subtract days.
- Time Zone Converter - Convert a time between any two time zones.
- Military Time Converter - Convert between 24-hour and 12-hour time.
- Decimal Hours Calculator - Convert hours:minutes to decimal and back.
- Add or Subtract Time Calculator - Add or subtract hours and minutes from a time.
FAQs
What are decimal hours?
Minutes expressed as a fraction of an hour - 30 minutes is 0.50 - used by payroll.
How does 24-hour time work?
Hours run 00 to 23 with no AM/PM; 1300 is 1:00 PM.
How do I handle overnight shifts?
Use the duration tool's next-day option so the hours calculate correctly.
Does the time-zone tool handle daylight saving?
Yes - it uses the current rules for the chosen date.
Why convert to decimal before paying?
Payroll multiplies the rate by decimal hours, not hours and minutes.