Add or subtract hours and minutes, find the total duration between two times, or calculate a new time by adding/subtracting hours from a start point. Supports overnight spans and multiple time entries.
Select from three modes: Duration (find the time between a start and end time), Add/Subtract (add or remove hours/minutes from a time), or Sum Multiple (add a list of time values together). Each mode has its own clear input layout.
Input times in 12-hour (AM/PM) or 24-hour format — the tool accepts both. For duration calculations, toggle the overnight switch if your end time is the next day. For sum mode, add as many time rows as you need with the + button.
Results display in both HH:MM format and decimal hours (e.g. 8h 30m = 8.50 hours). Decimal hours are used for payroll, billing and timesheet calculations. Copy either format to your clipboard with one click.
Select Duration mode, enter your start time (e.g. 09:00) and end time (e.g. 17:30). The calculator shows 8 hours 30 minutes = 8.50 decimal hours. If your shift crosses midnight (e.g. 22:00 to 06:00), toggle the Overnight switch and the tool correctly calculates the 8-hour span without showing a negative result.
Decimal hours express time as a number with a decimal fraction — 8 hours 30 minutes = 8.50 hours. Payroll and billing software uses decimal hours because multiplying by an hourly rate is straightforward: 8.50 hours × $20/hr = $170.00. Converting HH:MM to decimal: divide minutes by 60 and add to hours.
Switch to Sum Multiple mode and add a row for each time duration. Enter hours and minutes for each entry — for example, three days with 7h 30m, 8h 15m and 6h 45m. The total accumulates automatically. This is useful for weekly timesheet totals, project hour tracking and invoice preparation.
Yes — use Add/Subtract mode. Enter your start time and the number of hours and minutes to add (or subtract). The result shows the new time in both 12-hour and 24-hour format. For example: 2:30 PM + 3h 45m = 6:15 PM. Cross-midnight calculations are handled automatically.
When a shift crosses midnight, toggle the Overnight switch. This tells the calculator that the end time is on the following day, allowing it to correctly compute e.g. 22:00 to 06:00 as 8 hours rather than showing -16 hours. Without this switch, the tool assumes start and end are on the same day.
The Hours Calculator focuses on practical time arithmetic — start/end times, shift duration, adding/subtracting hours from a given time. The Time Duration Calculator focuses on adding and subtracting durations expressed as HH:MM:SS (including seconds) and is suited for media production timing, sports timing and precise interval calculations.
Divide the minutes by 60: 45 ÷ 60 = 0.75. Add to the hours: 7 + 0.75 = 7.75 decimal hours. Our calculator does this conversion automatically — both formats are always displayed side by side so you can copy either one directly into your invoice or timesheet.
Yes — use Sum Multiple mode and add a row for each day of the week. Enter each day's worked hours and minutes. The running total at the bottom shows your weekly hours in both HH:MM and decimal format. For a full weekly timesheet with break deductions and overtime tracking, use the dedicated Time Card Calculator.
There is no practical limit — you can calculate thousands of hours across multiple entries in Sum mode. The display correctly handles totals like 127 hours 45 minutes rather than rolling over at 24. This makes it suitable for project billing across long timeframes.
The most common source of error in manual calculations is forgetting to convert minutes correctly (treating :30 as 0.3 instead of 0.5) or not handling overnight spans. Our calculator uses precise integer arithmetic in minutes to avoid any floating-point rounding errors in the HH:MM output.
