How Do You Calculate FTE Security Guards?

How to calculate FTE security guards: the formula, 3 worked examples, and why ~4.2–4.5 FTEs cover one 24/7 post. Get the math right.

Yonah Nathan — Co-founder & Head of Product

Published July 12, 2026 Updated July 23, 2026 5 min read

Running scheduling across 400+ officers in four markets, I use one number more than any other: FTEs. Headcount tells me how many W-2s I have. FTEs tell me how much security I'm actually delivering. Here's the math, worked all the way through.

What's the formula for converting guard hours to FTEs?

FTEs = total scheduled hours per week ÷ 40

That's it. One full-time equivalent is 40 scheduled hours per week — the standard full-time workweek under common US practice (and the baseline the ACA and Bureau of Labor Statistics conventions orbit, though definitions vary by context). Everything else is arithmetic. Three worked examples:

Example 1 — a simple full-time roster. 30 guards, each scheduled 40 hours/week. 30 × 40 = 1,200 scheduled hours/week. 1,200 ÷ 40 = 30 FTEs. Headcount and FTEs match only in this clean case.

Example 2 — a part-time-heavy roster. 45 part-timers averaging 24 hours/week. 45 × 24 = 1,080 scheduled hours/week. 1,080 ÷ 40 = 27 FTEs. You have 45 people on payroll but deliver 27 full-time equivalents of coverage. Any per-user software license is charging you for 45; your revenue is built on 27.

Example 3 — a realistic mixed roster.

• 18 full-timers × 40 hrs = 720 hrs
• 12 part-timers × 24 hrs = 288 hrs
• 6 flex/on-call officers × 12 hrs = 72 hrs

Total: 1,080 scheduled hours/week ÷ 40 = 27 FTEs from 36 people. In my experience this shape — headcount running 25–35% above FTEs — is typical for commercial guard companies, because part-time and flex coverage is how you survive an industry where annual turnover is commonly cited at 100%+.

Why do FTEs beat headcount for planning?

Because clients buy hours, not people. A contract for a 24/7 post is a contract for 168 hours a week — the client doesn't care whether you deliver it with four people or seven. When you plan in headcount, you systematically misjudge:

• Bids. Pricing a post means costing the hours, with burden and overtime exposure — FTE math is the first line of the bill-rate build-up we walk through in how to price security guard services.
• Capacity. "Can we take this new account?" is a question about uncommitted hours, not idle bodies.
• Growth tracking. Hiring 10 part-timers looks like growth in headcount; it might be 6 FTEs of actual new capacity.

And there's a second reason that hits your software budget directly: pricing. Per-user guard software charges you for headcount — every part-timer and flex officer is a full license. Per-hour pricing charges for FTEs — the coverage you actually schedule and bill. On the mixed roster above, that's the difference between paying for 36 seats and paying for 27 FTEs. We compare the models in detail in per-user vs per-hour guard software pricing. It's also why SNTNL prices on scheduled hours: our plans are quoted in FTEs (one FTE = 40 scheduled hours/week), with unlimited users, so a part-time-heavy roster doesn't inflate your bill. Details on /pricing.

How many FTEs does a 24/7 post require?

The most common staffing question in this industry, and the one most often answered wrong. Here's the math.

Step 1 — hours to cover: 24 hours × 7 days = 168 hours/week.

Step 2 — raw FTEs: 168 ÷ 40 = 4.2 FTEs. That's the theoretical minimum if nobody ever takes a day off.

Step 3 — apply an absence factor. Guards take vacation, get sick, attend training, and serve jury duty. If each officer is genuinely available for roughly 37–38 productive scheduled hours out of a 40-hour week once you spread annual leave and absences across the year (about a 5–7% absence load), you need:

168 ÷ 37.5 ≈ 4.5 FTEs to reliably hold one 24/7 post.

That gap between 4.2 and 4.5 is where thin operators get hurt: staff the post at exactly 4.2 and every absence becomes an overtime shift or an open post. Overtime at time-and-a-half on wages commonly running $15–20/hour erodes margin fast; an open post can erode the whole contract — that's the churn math from what losing a security contract really costs.

Across Ranger Guard's markets — Houston, Corpus Christi, Las Vegas, and Florida — the durable pattern is that 24/7 posts staffed with realistic absence factors run on planned straight-time, while posts staffed at the theoretical minimum bleed unplanned overtime week after week.

What are the common FTE calculation mistakes?

1. Counting headcount as capacity. 40 people is not 40 FTEs unless every one of them is scheduled 40 hours. It almost never is.
2. Ignoring overtime in the divisor. FTEs are scheduled hours ÷ 40. If your roster only balances because officers routinely work 48-hour weeks, you don't have enough FTEs — you have an overtime bill pretending to be a staffing plan.
3. Forgetting the absence factor on 24/7 math. Staffing 4.2 when reality needs ~4.5 turns every PTO request into a crisis.
4. Using annual math when weekly is cleaner. The annual version (total hours ÷ 2,080) works, but weekly scheduled hours ÷ 40 matches how guard rosters are actually built and catches drift faster.
5. Trusting the schedule instead of the record. Scheduled FTEs are the plan; delivered hours are the truth. GPS-verified clock-ins tell you the difference — see GPS-verified clock-in and geofencing — and the gap between the two is exactly where billing disputes and revenue leakage live.

If you'd like to see FTE-based scheduling, GPS-verified hours, and delivered-vs-scheduled reporting running live in a real four-market operation, book a demo — bring your roster and we'll do the math on it together.