Tinker 
How to use it
Type the start and end times in 24-hour format (17:30) or 12-hour format with AM or PM (5:30 PM). Add any unpaid break in minutes. The result shows the duration in hours and minutes, the same figure as decimal hours for timesheets and payroll, and the total in minutes.
The formula
Each time is converted to minutes after midnight (hours × 60 + minutes). The start is subtracted from the end. If the answer is negative, the end time is on the next day, so 1,440 minutes (24 hours) are added. The break is then subtracted. Decimal hours are total minutes divided by 60, rounded to two places.
Worked example
A night shift runs from 22:00 to 06:15 with no break. 22:00 is 1,320 minutes after midnight and 06:15 is 375. 375 − 1,320 = −945, so add 1,440 to get 495 minutes. That is 8 hours 15 minutes, or 8.25 decimal hours.
A day shift from 9:15 AM to 5:45 PM with a 45-minute lunch: 1,065 − 555 = 510 minutes, minus 45 = 465 minutes, which is 7 hours 45 minutes or 7.75 hours.
Practical tips
Use decimal hours when multiplying by an hourly rate: 7.75 hours at 20 per hour is 155, whereas reading 7:45 as 7.45 would underpay. Spans of 24 hours or more cannot be shown from clock times alone; split very long periods into separate days. Identical start and end times give zero.
Frequently asked questions
How do I convert minutes to decimal hours?
Divide the minutes by 60. 15 minutes is 0.25 hours, 30 is 0.5, 45 is 0.75 and 20 is about 0.33.
Does it work for shifts past midnight?
Yes. When the end time is earlier than the start time, the calculator assumes the end is the next day and adds 24 hours.
Is 12:00 PM noon or midnight?
12:00 PM is noon and 12:00 AM is midnight. In 24-hour format these are 12:00 and 00:00.
Can I enter several breaks?
Add them together and enter the total, for example a 30-minute lunch plus two 15-minute rests is 60 minutes.