Time Calculator: Clock In Out, Convert and Decimal
Track work hours, convert between time units, and convert time to decimal in one free tool. No sign-up required.
Time Unit Conversion Reference Table
| Unit | Symbol | Seconds | Minutes | Hours | Days |
|---|---|---|---|---|---|
| Nanosecond | ns | 0.000000001 | 1.67 × 10⁻¹¹ | 2.78 × 10⁻¹³ | 1.16 × 10⁻¹⁴ |
| Microsecond | µs | 0.000001 | 1.67 × 10⁻⁸ | 2.78 × 10⁻¹⁰ | 1.16 × 10⁻¹¹ |
| Millisecond | ms | 0.001 | 0.0000167 | 2.78 × 10⁻⁷ | 1.16 × 10⁻⁸ |
| Second | s | 1 | 0.016667 | 0.000278 | 0.0000116 |
| Minute | min | 60 | 1 | 0.016667 | 0.000694 |
| Hour | h | 3,600 | 60 | 1 | 0.041667 |
| Day | d | 86,400 | 1,440 | 24 | 1 |
| Week | wk | 604,800 | 10,080 | 168 | 7 |
| Month (avg) | mo | 2,628,000 | 43,800 | 730 | 30.4167 |
| Year (365 d) | yr | 31,536,000 | 525,600 | 8,760 | 365 |
| Decade | dec | 315,360,000 | 5,256,000 | 87,600 | 3,650 |
| Century | c | 3,153,600,000 | 52,560,000 | 876,000 | 36,500 |
| Sidereal Day | d (sid) | 86,164.09 | 1,436.07 | 23.9345 | 0.9973 |
How to Use the Time Calculator
This time calculator combines three essential time tools into one page. You can track work hours with clock in and clock out entries, convert any time unit into another, or convert hours and minutes in hh:mm:ss format into decimal form. Each tool is accessible through the tabs above the calculator card.
Choose a calculator tab: Time Clock, Time Converter, or Time to Decimal.
Enter your values. For the time clock, add your start and end times. Add multiple periods if needed.
Click Calculate or Convert. Press Enter to trigger calculation from any input field.
Read your results table. Key values are highlighted. Use Clear to reset all fields.
How the Time Clock Calculator Works
The time clock calculator works by subtracting your clock in time from your clock out time. The result is expressed in total hours and minutes, and also in decimal hours for use on a timesheet.
Single and Multiple Shift Periods
Many workers have split shifts or take unpaid meal breaks. The time clock tool lets you add multiple clock in and clock out pairs in one calculation. Each period is computed independently, then all periods are summed. Any unpaid break minutes you enter are subtracted from the total before the final result is shown.
Converting Worked Hours to Decimal
Payroll systems often require time entered as a decimal rather than hours and minutes. The formula is straightforward.
For example, 7 hours and 30 minutes of work equals 7 + (30 / 60) = 7.5 decimal hours. This figure is then multiplied by an hourly rate to calculate pay.
Overnight and Cross-Midnight Shifts
If your clock out time is earlier than your clock in time, the calculator automatically adds 24 hours to the end time, correctly handling overnight shifts such as 10:00 PM to 6:00 AM.
How to Convert Time Units
Time unit conversion uses a fixed conversion factor that links every unit back to seconds. To convert from one unit to another, you multiply by the factor for the starting unit to reach seconds, then divide by the factor for the target unit.
The Universal Conversion Formula
For example, to convert 2 hours to minutes, multiply 2 by 3,600 seconds per hour, then divide by 60 seconds per minute. The result is 120 minutes.
Months and Years in This Calculator
Months are calculated using an average of 30.4167 days per month, which equals 365 days divided by 12 months. Years are calculated as exactly 365 days. The calculator does not account for leap years or variable month lengths, which is standard practice for time conversion purposes.
What Is a Shake?
A shake is an informal unit of time used in nuclear physics, equal to 10 nanoseconds or 0.00000001 seconds. It was coined during atomic bomb research in the 1940s and is still occasionally referenced in physics literature.
Sidereal vs Solar Time
A sidereal day is the time Earth takes to rotate once relative to distant stars, equal to 23 hours, 56 minutes, and 4.09 seconds. A solar day is 24 hours. The difference of about 4 minutes accumulates because Earth also travels along its orbit around the Sun, requiring a slight extra rotation to bring the Sun back to the same position in the sky.
How to Convert Time to Decimal
Converting time to decimal format is essential for payroll, billing, and data analysis. The time to decimal calculator takes hours, minutes, and seconds in hh:mm:ss format and returns three results: decimal hours, decimal minutes, and total seconds.
Formula for Decimal Hours
Formula for Decimal Minutes
Formula for Total Seconds
Common Time to Decimal Conversions
Below are frequently used time-to-decimal values for quick reference:
- 15 minutes = 0.25 hours
- 30 minutes = 0.50 hours
- 45 minutes = 0.75 hours
- 20 minutes = 0.3333 hours
- 10 minutes = 0.1667 hours
- 1 hour 15 minutes = 1.25 hours
- 7 hours 30 minutes = 7.5 hours
- 8 hours 45 minutes = 8.75 hours
Time Calculation for Payroll and Timesheets
Time calculation for payroll involves converting hours and minutes worked into a decimal figure, then multiplying by an hourly wage to arrive at gross pay.
Step by Step Payroll Example
- Record clock in as 8:00 AM and clock out as 5:30 PM.
- Calculate total worked time: 9 hours and 30 minutes.
- Convert 30 minutes to decimal: 30 / 60 = 0.5.
- Total decimal hours: 9.5 hours.
- Multiply by hourly rate: 9.5 × $15.00 = $142.50 gross pay.
Weekly Timesheet Totals
To calculate a weekly total, repeat the above for each workday and sum the decimal hours. For example, five days of 8.5 decimal hours equals 42.5 total hours, with 2.5 hours of overtime above the standard 40 hour week in most jurisdictions.