24/7 post: how many people you need and what it costs

A customer asks you to quote round-the-clock coverage for the gatehouse at their plant, every day of the year. The quick math looks easy: three eight-hour shifts, three people. You sign, you start, and in the first month someone gets sick, someone else goes on vacation and nobody wants to pull a double on Sunday. You end up covering with overtime, with a supervisor standing in, or worse, with an empty post. The contract that looked profitable starts losing money from the first payroll.

The mistake is not in operations; it is in the initial math. A 24/7 post is not covered by three people, and the cost is not three salaries. This guide shows you how to do the full calculation, even if you keep it in a spreadsheet.

Step 1: calculate the hours to cover

A post that never shuts down needs people every hour of the year:

• Hours per week: 24 × 7 = 168 h.
• Hours per year: 24 × 365 = 8,760 h.
• Monthly average: 8,760 ÷ 12 = 730 h.

Use the monthly average (730 h), not the hours of a specific month: that way the calculation does not change between February and March and the monthly price stays stable.

If the post is not 24/7 (say, Monday to Saturday from 7:00 to 19:00), apply the same logic: hours per day × days per week × 52 ÷ 12.

Step 2: define the hours one person works

Here comes a parameter you should not make up: the regular monthly hours per person, rest days, and how holidays and night or Sunday work are handled. That is set by labor regulations, your employment contract and your internal policy, and you should validate it with your labor advisor or your HR team.

For the example we will use a hypothetical figure: each person has 180 regular hours per month.

With that, the naive math would be 730 ÷ 180 = 4.06 people. It is clearly not three. But it is not four either, because the most important part is still missing.

Step 3: apply the coverage factor

A hired person is not available for all of their hours. There are vacations, sick leave, absences, training and permits. Those hours must be covered by someone else.

1. Take the last 12 months of history (attendance records, leave and vacation summary).
2. Add up, per person, the contracted hours and the hours not worked for any reason.
3. Calculate availability:

Availability = (contracted hours − hours not worked) ÷ contracted hours

4. The coverage factor is its inverse:

Coverage factor = 1 ÷ availability

Suppose that in your history, out of every 100 contracted hours, 12 were not worked. Availability is 0.88 and the coverage factor is 1 ÷ 0.88 = 1.136.

Now the full calculation:

People per post = hours to cover ÷ (hours per person × availability)

730 ÷ (180 × 0.88) = 730 ÷ 158.4 = 4.61 people.

If the post stands alone, round up to 5. If you run several similar posts in the same city, a shared relief pool pays off: for 10 posts you need 46.1 people, that is 47, not 50. That difference is margin.

Step 4: calculate the real cost of the post

The most expensive mistake is quoting with the salary. What a person really costs is their fully loaded labor cost: salary, employer contributions, provisions (bonuses, vacations, severance) and any other benefit that applies. Which items go in and in what proportion is defined by your accountant or labor advisor; treat it as a variable in your sheet, not a fixed figure.

Add to that what the post consumes even if it is not on payroll:

• Prorated supervision (one supervisor covers several posts).
• Uniforms, protective equipment, supplies and communications.
• Administrative overhead you allocate to each contract.

Suppose these hypothetical monthly figures for a standalone 24/7 post:

Item	Calculation	Bs per month
Staff	5 people × Bs 5,000 loaded cost	25,000
Supervision	Bs 8,000 ÷ 10 posts	800
Uniforms, equipment and supplies	Monthly proration	400
Allocated overhead	Fixed amount per contract	1,800
Total cost of the post		28,000
Cost per covered hour	28,000 ÷ 730	38.36

Step 5: set the price and the margin

Margin is calculated on price, not on cost:

Price = total cost ÷ (1 − target margin)

If you want a 15% margin on price: 28,000 ÷ 0.85 = 32,941, which you round to Bs 33,000 per month. Check: (33,000 − 28,000) ÷ 33,000 = 15.2%.

Note the detail that often trips people up: if instead you add 15% to cost (28,000 × 1.15 = 32,200), your real margin on price is 13%, not 15%.

Two warnings:

• Agree with your accountant whether the price you quote includes taxes or whether they are added on top. Do not mix both in the same sheet.
• Include an adjustment clause in the contract for when labor costs change. If wages go up and the price does not, the margin disappears.

Common mistakes

• Dividing hours by the workday and rounding down. 730 ÷ 180 gives 4.06; with four people you are short even before absences.
• Forgetting the coverage factor. Vacations are certain and sick leave is almost certain. If they are not in the price, you pay for them.
• Quoting with salary instead of loaded cost. The gap between the two is exactly what your advisor helps you calculate.
• Always covering absences with overtime. It costs more, wears people out and drives turnover. Use it as an exception, not a plan.
• Not prorating supervision and relief staff. The supervisor who tours the posts is a cost of every contract.
• Using a made-up coverage factor. Measure it with your own history and update it every year.

Indicators to check that the math still holds

Indicator	How it is calculated	How to read it
Post coverage	Hours covered ÷ hours contracted with the customer	Below 100% means uncovered posts: risk of complaints or penalties.
Absenteeism	Unplanned absence hours ÷ scheduled hours	If it rises, your real coverage factor is already higher than the one you quoted with.
Relief overtime	Overtime paid to cover absences ÷ total hours	If it grows month after month, your relief pool is short of people.
Real margin per contract	(Invoiced − real monthly cost) ÷ invoiced	Compare it with the quoted margin; the gap tells you where the money goes.
Turnover	Leavers in the month ÷ average active headcount	High turnover raises hiring, training and on-post mistakes.

Checklist before quoting

• Monthly hours to cover calculated with the annual average.
• Regular hours, rest days, holidays and night work validated with your advisor.
• Coverage factor measured with the last 12 months of history.
• Loaded labor cost defined with your accountant, not just the salary.
• Supervision, uniforms, equipment and overhead prorated.
• Margin calculated on price.
• Taxes and adjustment clause defined in the contract.

If you want to automate it

All of this works in a spreadsheet; the hard part is feeding it real attendance data every month. An ERP like MKA can receive clock-ins from the biometric readers at each site, apply leave, vacations and shift swaps, and pass the confirmed summary to a payroll that calculates with the formulas your team defines, so absenteeism and real cost come out of the system (see the solution for labor-intensive companies).