How to use the shift coverage calculator
- Enter the people needed on duty in every open hour, the hours open and the days open, such as Mon-Sat.
- List each shift with its days, start and end times, and the number of people on it. A shift that ends earlier than it starts runs past midnight.
- Read the person-hours short, over and needed, and the table of understaffed times by day.
- Use the coverage table to see how many people are on duty and how many are needed in each block of time.
Formula
the week is cut into 15 minute slots
people on duty in a slot = sum of the people on every shift that covers the slot on that day
short in a slot = max(0, needed - on duty), over in a slot = max(0, on duty - needed)
person-hours short = sum of short over all slots x 15 minutes / 60
Needed people are placed on every slot between the opening and closing times on the days open. A shift past midnight adds its people to the early hours of the next day.
A shop open 8 AM to 8 PM, Monday to Saturday
The shop needs 2 people in every open hour, which is 12 hours x 6 days x 2 = 144 person-hours. The shifts are an opening shift with 1 person from 8 AM to 2 PM Monday to Saturday, a midday shift with 1 person from 10 AM to 6 PM Monday to Friday, and a closing shift with 2 people from 2 PM to 8 PM Monday to Saturday. That schedules 36 + 40 + 72 = 148 person-hours.
Even though the total is above the need, the week has gaps. Monday to Friday from 8 AM to 10 AM has 1 person for 2 needed, and Saturday from 8 AM to 2 PM has 1 for 2, which adds up to 16 person-hours short. From 2 PM to 6 PM Monday to Friday there are 3 people for 2 needed, which is 20 person-hours over. Moving the midday shift earlier would close most of the gap.
Reading the tables
The first table lists only the blocks where fewer people are on duty than needed, so it is your to-do list. The second shows every block, with a note of whether the block is covered, short or over. Blocks are merged when the number on duty and the number needed stay the same, so a long quiet stretch is one line.
To plan breaks around coverage, see the Staggered Break Schedule Generator, to work out labor hours from coverage the Staffing Hours Calculator, and to rotate shifts fairly the Shift Rotation Schedule Generator.
What this page does not decide
Breaks, time off, minimum rest between shifts, overtime and local scheduling rules are not modeled. The need is the same in every open hour, so peaks and quiet times are not distinguished. Check your own policies and any laws that apply before publishing a schedule.
More scheduling tools
For other schedules and time totals, try the Time Range Calculator, Backward Schedule Generator and Guest Attendance Forecast Calculator.
Assumptions and limits
- The same number of people is needed in every open hour.
- A shift applies to every day listed and has the same people each day.
- Shift and opening times are counted in 15 minute slots, so times that are not on a quarter hour are approximate.
- Breaks and absences are not removed from a shift.
Frequently asked questions
How do I check whether a schedule covers every hour?
Count the people on duty in each slice of the day and compare with the number needed. The tool does this for each 15 minute slot of a week and lists the blocks that fall short.
What are person-hours?
One person working for one hour. Two people covering four hours is eight person-hours.
Why can I be short and over in the same week?
Total hours can match or exceed the need while the shifts overlap in some hours and leave gaps in others. Moving shift times, not adding people, can fix that.
How are shifts that cross midnight handled?
If the end time is earlier than the start, the shift runs into the next day. A Friday 10 PM to 6 AM shift covers late Friday and early Saturday.