Last updated: March 2026
What Is the Hours Calculator?
The hours calculator is a free tool that lets you add, subtract, and convert time values instantly. Whether you need to total up hours worked across multiple shifts, convert between decimal hours and HH:MM format for payroll, or calculate a project's total duration from individual tasks, this calculator handles it all in real time as you type.
Unlike basic time calculators, this tool includes three modes. The Add/Subtract mode lets you combine up to 20 time entries with individual plus or minus toggles. The Convert Formats mode instantly translates between HH:MM:SS, decimal hours, total minutes, and total seconds. The Payroll Hours mode provides a full weekly timesheet with clock in/out times, break deductions, and automatic overtime splitting at 40 hours.
Every calculation happens instantly in your browser. No data is sent to any server, no signup is required, and you can export your results as CSV or JSON at any time.
How to Add Hours and Minutes
Adding hours and minutes requires handling the base-60 system correctly. When minutes exceed 59, you carry over to hours. For example, 2 hours 45 minutes plus 1 hour 30 minutes: add the minutes first (45 + 30 = 75 minutes), carry 60 minutes as 1 hour, leaving 15 minutes. Then add hours: 2 + 1 + 1 (carried) = 4 hours. The result is 4 hours 15 minutes.
The same principle applies to seconds. If you add 3:45:50 and 2:20:25, the seconds total 75, which becomes 1 minute and 15 seconds. The minutes then total 45 + 20 + 1 = 66, which becomes 1 hour and 6 minutes. The final result is 6:06:15. This calculator handles all of these carries automatically.
For subtraction, the process works in reverse. If you subtract and a field goes negative, you borrow from the next larger unit. Subtracting 45 minutes from 2 hours 15 minutes: borrow 1 hour as 60 minutes, making it 1 hour 75 minutes. Then 75 - 45 = 30 minutes. Result: 1 hour 30 minutes.
Understanding Decimal Hours for Payroll
Most payroll systems use decimal hours instead of HH:MM because they are easier to multiply by hourly rates. In decimal format, 7 hours and 30 minutes becomes 7.50 hours. Multiplying 7.50 by a $25 hourly rate gives $187.50 directly, with no extra conversion needed.
The most common time-to-decimal conversions to memorize are: 15 minutes = 0.25 hours, 30 minutes = 0.50 hours, and 45 minutes = 0.75 hours. For any number of minutes, divide by 60 to get the decimal: 20 minutes / 60 = 0.333 hours. Many employers round to the nearest quarter hour (0.25) for payroll purposes.
Under the Fair Labor Standards Act (FLSA), non-exempt employees earn overtime at 1.5 times their regular rate for hours worked beyond 40 in a workweek. Some states, like California, also require daily overtime after 8 hours. This calculator uses the federal 40-hour weekly threshold by default.
Frequently Asked Questions
How do I add hours and minutes together?
Enter each time value in the Add/Subtract tab using the HH, MM, and SS fields. The calculator adds all entries in real time and displays the total in HH:MM:SS, decimal hours, total minutes, and total seconds. You can add up to 20 separate time entries at once.
How do I convert decimal hours to hours and minutes?
Use the Convert Formats tab and select Decimal Hours as the input format. Enter a value like 2.75 and the calculator instantly shows the equivalent in HH:MM:SS (2:45:00), total minutes (165), and total seconds (9900). To convert manually, multiply the decimal portion by 60 to get minutes: 0.75 x 60 = 45 minutes.
How does overtime calculation work?
The Payroll Hours tab calculates weekly totals and automatically splits hours into regular time (up to 40 hours) and overtime (anything over 40 hours). If you enter an hourly rate, it computes gross pay using 1.0x for regular hours and 1.5x for overtime hours, following standard FLSA rules.
Can I subtract time with this calculator?
Yes. Each row in the Add/Subtract tab has a +/- toggle button. Click it to switch any entry to subtraction mode. The total updates instantly, and negative results are displayed with a minus sign. This is useful for calculating time differences or adjustments.
What is the difference between decimal hours and HH:MM format?
HH:MM format uses a base-60 system where 1:30 means 1 hour and 30 minutes. Decimal hours use base-10 where 1.50 means 1 and a half hours. They represent the same amount of time but decimal hours are easier for multiplication (e.g., 7.5 hours x $20/hr = $150). Payroll systems often use decimal hours for this reason.