Hours Calculator

Hours Calculator

To calculate hours between two times, convert both to minutes from midnight and subtract. For 9:00 AM to 5:30 PM: end (1,050 min) minus start (540 min) = 510 minutes = 8 hours 30 minutes. Use the Add mode to total multiple time durations for timesheets.

Start Time

End Time

Key Takeaways

Time Between mode calculates the duration from a start time to an end time, automatically handling midnight crossovers.
Add/Subtract mode lets you combine multiple time durations (useful for totaling work hours or subtracting breaks).
Decimal hours = hours + (minutes / 60). For example, 7 hours 30 minutes = 7.50 decimal hours.
Common decimal conversions: 15 min = 0.25 hr, 30 min = 0.50 hr, 45 min = 0.75 hr, 6 min = 0.10 hr.
For timesheets, calculate each shift separately, subtract lunch breaks, then add all net shift times together.

How to Calculate Time Between Two Times

Calculating the time between two clock times requires converting both times to a common reference point, then finding the difference. The simplest method is converting both times to minutes from midnight (12:00 AM), subtracting the start from the end, and converting the result back to hours and minutes.

For example, to find the time between 8:45 AM and 4:20 PM: first convert to minutes from midnight. 8:45 AM = (8 x 60) + 45 = 525 minutes. 4:20 PM = (16 x 60) + 20 = 980 minutes. The difference is 980 - 525 = 455 minutes. Convert back: 455 / 60 = 7 hours with 35 minutes remaining. The answer is 7 hours 35 minutes.

When a time period crosses midnight (e.g., 10:00 PM to 6:00 AM), add 1,440 (24 x 60) to the end time before subtracting. 10:00 PM = 1,320 minutes. 6:00 AM = 360 minutes. Add 1,440: 360 + 1,440 = 1,800. Duration: 1,800 - 1,320 = 480 minutes = 8 hours.

The Time Difference Formula

Duration (minutes) = End Time (minutes from midnight) - Start Time (minutes from midnight)

Hours = floor(Duration / 60), Minutes = Duration mod 60

Convert PM times to 24-hour format first: add 12 to hours for PM (except 12 PM stays 12). 12 AM becomes 0.

Dana logs her work hours for a kitchen renovation project. She arrived at the site at 7:15 AM and left at 3:45 PM with a 30-minute lunch break. Total elapsed: (15 x 60 + 45) - (7 x 60 + 15) = 945 - 435 = 510 minutes = 8 hours 30 minutes. Minus 30-minute lunch: 8 hours net work time. She enters 8.00 on her timesheet.

Decimal Hours Conversion

Payroll and invoicing systems typically require time in decimal hours rather than hours and minutes. To convert, divide the minutes by 60 and add to the hours. The table below shows common conversions.

Minutes	Decimal Hours	Minutes	Decimal Hours
5 min	0.08	35 min	0.58
10 min	0.17	40 min	0.67
15 min	0.25	45 min	0.75
20 min	0.33	50 min	0.83
25 min	0.42	55 min	0.92
30 min	0.50	60 min	1.00

Decimal hours = minutes / 60, rounded to two decimal places.

Adding and Subtracting Time

To add time durations, add the hours and minutes separately. If the total minutes reach 60 or more, convert each group of 60 minutes to 1 hour. For example:

2h 45m + 1h 30m + 3h 50m = (2 + 1 + 3)h + (45 + 30 + 50)m = 6h 125m = 6h + 2h 5m = 8h 5m.

Subtracting works in reverse. If minutes go negative, borrow 1 hour (60 minutes). For example: 5h 15m - 2h 40m. Since 15 - 40 is negative, borrow: (5-1)h (15+60-40)m = 4h 35m = 2h 35m.

Common Time Calculations

The table below shows standard work shift durations for reference.

Shift	Start	End	Duration	Net (minus 30m lunch)
Standard	9:00 AM	5:00 PM	8h 00m	7h 30m
Early	7:00 AM	3:30 PM	8h 30m	8h 00m
Late	10:00 AM	6:30 PM	8h 30m	8h 00m
Night	10:00 PM	6:00 AM	8h 00m	7h 30m
Part-time	9:00 AM	1:00 PM	4h 00m	4h 00m

Net hours assume a 30-minute unpaid lunch break for shifts of 6+ hours. Actual break policies vary by employer and jurisdiction.

For tracking work hours across a full week, calculate each day's net hours separately, then use the Add mode to total them. You can use the salary to hourly converter to find your hourly rate, the time duration calculator for durations spanning multiple days, or the percentage calculator to figure overtime pay rates as a percentage of your base wage.

This calculator provides time arithmetic for informational purposes. Payroll calculations may involve additional factors such as overtime rules, rounding policies, and break requirements that vary by employer and jurisdiction.

Frequently Asked Questions

How do I calculate hours between two times?

Convert both times to minutes from midnight, then subtract the start from the end. For example, 9:30 AM to 5:15 PM: 9:30 AM = 570 minutes, 5:15 PM = 1,035 minutes. Difference = 1,035 - 570 = 465 minutes = 7 hours 45 minutes. If the end time is earlier than the start (crosses midnight), add 1,440 minutes (24 hours) to the end time before subtracting.

How do I convert hours and minutes to decimal hours?

Divide the minutes by 60 and add to the hours. For example, 7 hours 45 minutes = 7 + (45/60) = 7.75 decimal hours. Common conversions: 15 min = 0.25, 30 min = 0.50, 45 min = 0.75. Decimal hours are used on timesheets, invoicing, and payroll systems.

How do I add multiple time durations together?

Add the hours and minutes separately. If total minutes equal or exceed 60, divide by 60 to get additional hours and take the remainder as minutes. Example: 2h 45m + 3h 30m = 5h 75m = 6h 15m (since 75 min = 1h 15m). The same process works for any number of time entries.

What if my time crosses midnight?

The calculator automatically handles times that cross midnight. If the end time appears to be earlier than the start time (e.g., 10:00 PM to 2:00 AM), the calculator adds 24 hours to the end time. The result in this example would be 4 hours.

How do I calculate work hours for a timesheet?

Enter your clock-in time as the start and clock-out time as the end. The calculator shows total hours in both standard (hours and minutes) and decimal format. For a lunch break, calculate morning and afternoon separately, then use the Add mode to combine them. Most payroll systems use decimal hours (e.g., 8.25 instead of 8 hours 15 minutes).

How do I subtract time?

In Add/Subtract mode, change the operator to the minus sign (−) for any time entry. The calculator subtracts that duration from the total. This is useful for removing break time from total work hours. For example, 8h 30m total minus 0h 45m lunch = 7h 45m net work time.

How often should I track my work hours?

Record your hours daily, ideally at clock-in and clock-out. Waiting until the end of the week introduces rounding errors and forgotten breaks. Daily tracking ensures accurate timesheets, correct overtime calculations, and reliable project billing. Use the calculator at the end of each pay period to verify your totals before submission.