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Shift Relief Factor and FTE Coverage Calculator

A post that must be staffed around the clock needs far more than one employee per shift. The relief factor is the multiplier that turns posts into heads after leave, holidays and training.

Your numbers

Posts staffed at all times

posts

Stations or roles that must be covered every hour of operation.

Operating hours per week

168 for 24/7 operations, 120 for 24/5, 80 for two shifts of 5 days.

Weeks operating per year

weeks

Paid hours per employee per week

Vacation days per employee

days

Paid holidays not worked

days

Sick and other absence days

days

Training and meeting hours per year

Shift length

Annual loaded cost per employee

Your results

Relief factor

4.7895

Employees to hire or assign

Hours to cover per post per year

8,736

Paid hours per employee per year

2,080

Productive hours per employee

1,824

Employees needed (unrounded)

23.9474

Availability of a paid hour

87.7%

Annual cost of this crew

$1,632,000

Assumes absence days are fully backfilled by the crew and ignores overtime, floaters and part-time staff.

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Save results:

Employees needed vs vacation days

Sweeps Vacation days per employee from 0 to 30, holding your other inputs fixed.

Absence data from payroll and ERP

Optional: we can compile absence and overtime history by department for a staffing review.

Optional. The tool and every export work without this. No spam.

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How to use it

Enter the number of posts that must be staffed at all times and how many hours per week the plant runs. Add the paid hours per employee per week and the average days of vacation, holidays, sick leave and training they take. Choose the shift length so days convert to hours correctly. The result shows the relief factor, the number of employees needed and the annual cost.

Use actual absence history, not policy maximums
Run the model separately for 12-hour shift crews and 8-hour crews
Include leave of absence and long-term injury if material

Formula

Relief factor equals the hours a post must be covered per year divided by the productive hours one employee delivers per year. Productive hours are paid hours less leave hours and training hours. For a 24/7 post that is 8,736 hours, and with about 1,800 productive hours per employee the factor is near 4.8, so one post needs nearly five people. Multiply by posts and round up to get heads.

Reading the result

The relief factor is the number every shift manager should know. A factor lower than expected usually means leave is under-estimated. Use the chart to see how vacation days change headcount, which helps in policy discussions. Where the rounded head count is above the unrounded figure by a large amount, part-time or floater coverage may be cheaper than a full extra position.

Common mistakes

Do not divide 168 hours by 40 and call it 4.2 people, since that ignores all leave. Do not mix shift lengths without adjusting days to hours, because a 12-hour shift day removes 12 hours of availability. Finally, if you run overtime to cover leave, the cost will differ from this model, so compare it with the overtime versus added shift calculator.

Frequently Asked Questions

What is a relief factor?

It is the ratio of the hours a position must be covered to the productive hours one employee provides. A factor of 4.8 means one continuously staffed post requires 4.8 full-time employees once leave and training are considered.

Why is the answer different for 12-hour shifts?

A leave day removes more hours on a 12-hour crew. Set the shift length input to match so that vacation, holiday and sick days convert to the correct hours. Paid hours per week may also differ for rotating patterns.

Does this work for 4 on 4 off or 2-2-3 patterns?

Yes for the totals, because it works from annual hours covered and annual hours delivered. It does not build the roster itself. Use a schedule template to check that the pattern gives enough crews on each day.

Should I include absenteeism beyond sick days?

Yes. Add unpaid absences, leave of absence and long-term disability in the absence days input if they are not backfilled elsewhere. Using last year's actual total from HR is more accurate than a policy figure.

If you want absence, leave and overtime data pulled from payroll and the ERP to calibrate this model, we can build that report for your plant.

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