24/7 guard post
coverage calculator
A 24/7 post with one officer on duty needs 168 hours of coverage a week, which is 4.2 full-time officers at 40 hours — and about five once you allow for absences and turnover. This calculator works it out for any post: enter the hours, the days, the shift length, your overtime threshold and an absence buffer, and it returns the officers to hire, the weekly hours each one works and the overtime the schedule builds in. It is free, from CGuardPro, and runs in your browser.
Your post
24 for a round-the-clock post; 12 for a night-only post.
Seven for a post that never closes; five for a weekday post.
Usually 8 or 12. It has to divide the covered day evenly — 24 hours splits into 8s or 12s, 16 hours into 8s.
Hours per week after which overtime is paid. 40 under the federal FLSA rule; use your own if your contract or jurisdiction differs.
Extra headcount for vacation, sickness, training and the gap between a resignation and a hire. Take it from your own history; 10 is only a starting value.
Press Calculate. If your browser does not run JavaScript, the formula and a worked example are written out below.
What formula does the calculator use?
H = hours per day × days per week (weekly coverage hours)
S = H ÷ shift length (shifts per week)
FTE = H ÷ T (T = overtime threshold; nobody absent)
N = round up ( H × (1 + buffer) ÷ T ) (officers to hire)
Shifts split as evenly as possible: q = floor(S ÷ N), r = S − q × N
→ r officers work q + 1 shifts, the other N − r work q shifts
Average weekly hours per officer = H ÷ N
Built-in overtime = r × max(0, (q+1) × L − T) + (N − r) × max(0, q × L − T)
L is the shift length. The buffer adds headcount, not hours: the post still needs H hours a week, and the extra people are there so that a vacation or a resignation is covered at straight time instead of overtime. The calculator also shows what happens if you staff at the full-time-equivalent figure rounded down, which is where most built-in overtime comes from.
Worked example: a 24/7 post on 12-hour shifts
| Step | Calculation | Result |
|---|---|---|
| Weekly coverage | 24 × 7 | 168 h |
| Shifts per week | 168 ÷ 12 | 14 shifts |
| Full-time equivalents | 168 ÷ 40 | 4.2 |
| Officers to hire (10% buffer) | 168 × 1.10 ÷ 40 = 4.62, rounded up | 5 |
| Shift split at 5 officers | 14 = 4 × 3 + 1 × 2 | 4 officers × 36 h, 1 × 24 h |
| Average hours per officer | 168 ÷ 5 | 33.6 h |
| Built-in overtime at 5 | nobody passes 40 | 0 h a week |
| Built-in overtime at 4 | 14 = 2 × 4 + 2 × 3 → 2 × (48 − 40) | 16 h a week |
The same post on 8-hour shifts is 21 shifts a week. Five officers split them 5, 4, 4, 4, 4: one officer at 40 hours, four at 32, and no overtime. Four officers would split them 6, 5, 5, 5 — one officer at 48 hours, 8 of them overtime.
Frequently asked questions
How many guards does a 24/7 post need?+
At least 4.2 full-time equivalents with one officer on duty: 168 hours a week divided by 40. In practice that means four officers with some overtime, or five officers with none — and once you add a buffer for absences and turnover, most companies land on five per 24/7 post.
Why does the calculator round up?+
Because you cannot hire 4.62 people. The full-time-equivalent figure is shown too, so you can see how much of the last position is really needed — a part-time or shared relief officer may cover it across several posts.
What is built-in overtime?+
Overtime the schedule creates even when everyone shows up. Shifts are indivisible: with 12-hour shifts and a 40-hour threshold, an officer working four shifts in a week works 48 hours, eight of them at overtime. The calculator spreads the week's shifts as evenly as possible and adds up the hours past the threshold.
Does it account for California daily overtime?+
No. It applies a weekly threshold only. In California and other places with daily overtime rules, every hour past 8 in a workday is also overtime, which makes any 12-hour shift carry daily overtime. Check the rules where the post is.
Is anything I type stored or sent?+
No. The calculator is a script on this page; nothing leaves your browser.
From headcount to a schedule that holds
Used by 600+ security companies, CGuardPro generates each post’s schedule from its rotation, works out relief coverage for days off, and flags uncovered posts before the shift starts. Approved hours can go to Gusto as time sheets classified as regular, overtime and double overtime by the federal weekly rule and California daily rules.