Shift Coverage Calculator

Work out how many staff are needed to cover a rota around the clock, including relief.

About Shift Coverage Calculator

Round-the-clock cover needs far more people than positions, because each employee works only a fraction of the week and a further slice of their time is unavailable. The coverage factor for 24/7 working is typically between four and five employees per position. Rotas built without shrinkage look staffed on paper and collapse the first week someone takes leave, which is why the factor rather than the position count drives hiring.

Formula

Shift Coverage

Employees = coverage hours per week ÷ (contracted hours × (1 − shrinkage))

shrinkage: Paid time unavailable for the rota: leave, sickness, training
coverage factor: Employees needed per position to sustain the pattern

Worked example

With the default values below, Shift Coverage Calculator returns Employees Required of 18. Change any input above and every figure here is recalculated in your browser.

Inputs used

Positions to staff on each shiftminimum 1: 3
Shifts per dayaccepts 1–6: 3
Days per week to coveraccepts 1–7 days: 7 days
Contracted hours per employee per weekaccepts 1–60 h: 37.5 h
Shrinkage for leave, sickness and trainingaccepts 0–100 %: 22 %

Results

Employees Required: 18
Hours of Coverage Needed per Week: 504.0 h
Coverage Factor per Position: 2.00
Effective Hours per Employee: 29.3 h
Additional Employees Needed for Relief: 4.6

Step by step

1Values used
2Shift Coverage
3Employees Required= 18
4Hours of Coverage Needed per Week= 504.0 h
5Coverage Factor per Position= 2.00
6Effective Hours per Employee= 29.3 h
7Additional Employees Needed for Relief= 4.6

Assumptions and limits

The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
This is an estimate for general information and not professional financial, tax or legal advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Shift Coverage calculated?

Employees = coverage hours per week ÷ (contracted hours × (1 − shrinkage)) Round-the-clock cover needs far more people than positions, because each employee works only a fraction of the week and a further slice of their time is unavailable. The coverage factor for 24/7 working is typically between four and five employees per position.

Why does Shift Coverage matter?

Rotas built without shrinkage look staffed on paper and collapse the first week someone takes leave, which is why the factor rather than the position count drives hiring.

What values do I need to enter?

This calculator takes 5 inputs: Positions to staff on each shift, Shifts per day, Days per week to cover, Contracted hours per employee per week, Shrinkage for leave, sickness and training. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.