SOC Staffing Calculator
Size a SOC rota in FTE, including the 4.2–5 FTE per seat that genuine 24×7 coverage requires once shrinkage is funded.
About SOC Staffing Calculator
168 ÷ 40 is 4.2, which is why a single 24×7 seat needs at least 4.2 FTE before anyone takes a day off. Dividing by (1 − shrinkage) funds leave, sickness and training, which pushes a realistic seat to about 5.25 FTE — the number most SOC business cases are missing. Under-funded rotas fail predictably: the fifth person is cut in budget review, then every holiday is covered by overtime until people leave, and the vacancy makes the coverage gap permanent.
Formulas
SOC Staffing
FTE per seat = coverage hours per week ÷ contracted hours per FTE ÷ (1 − shrinkage). Total FTE = seats × FTE per seat, plus tier 2 and leadership.
- 168
- Hours in a week — the true cost of 24×7
- contracted hours
- Hours per FTE per week, usually 37.5–40
- shrinkage
- Leave, sickness, training and attrition, typically 18–25%
Leadership and cost
Team leads = (tier 1 + tier 2 FTE) ÷ span of control; annual cost = total FTE × fully loaded cost per FTE.
- span of control
- Analysts one lead can realistically manage, 6–10
- fully loaded cost
- A user-supplied assumption
Worked example
With the default values below, SOC Staffing Calculator returns Total FTE Required of 24.8. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Seats to staff concurrentlyaccepts 1–500 seats
- 3 seats
- Coverage modelone of 24×7×365 — 168 h/week, Extended, 16×7 — 112 h/week, Extended, 16×5 — 80 h/week, Business hours, 8×5 — 40 h/week
- 24×7×365 — 168 h/week
- Contracted hours per FTE per weekaccepts 20–60 hours/week
- 40 hours/week
- Shrinkage — leave, sickness, training, attritionaccepts 0–60 %
- 20 %
- Tier 2 analysts per tier 1 analystaccepts 0–3 ratio
- 0.4 ratio
- Analysts per team leadaccepts 2–40 analysts
- 8 analysts
- Fully loaded cost per FTEaccepts 0–1,000,000 $/year
- 95,000 $/year
Results
- Total FTE Required
- 24.8 FTE
- FTE per Seat≈4.2 for 24×7 before shrinkage, ≈5.25 with 20% shrinkage.
- 5.25 FTE
- Tier 1 FTE
- 15.8 FTE
- Tier 2 FTE
- 6.3 FTE
- Team Lead FTE
- 2.8 FTE
- Annual People Cost
- $2,356,594
- Rota Feasibility
- Viable 24×7 rota — confirm the shift pattern is legal for rest periods
Step by step
- 1Values used
- 2SOC Staffing
- 3Leadership and cost
- 4Total FTE Required= 24.8 FTE
- 5FTE per Seat= 5.25 FTE
- 6Tier 1 FTE= 15.8 FTE
- 7Tier 2 FTE= 6.3 FTE
- 8Team Lead FTE= 2.8 FTE
- 9Annual People Cost= 2,356,594
Assumptions and limits
- The result is derived only from the 7 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax 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.
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 SOC Staffing calculated?
FTE per seat = coverage hours per week ÷ contracted hours per FTE ÷ (1 − shrinkage). Total FTE = seats × FTE per seat, plus tier 2 and leadership. 168 ÷ 40 is 4.2, which is why a single 24×7 seat needs at least 4.2 FTE before anyone takes a day off. Dividing by (1 − shrinkage) funds leave, sickness and training, which pushes a realistic seat to about 5.25 FTE — the number most SOC business cases are missing.
Why does SOC Staffing matter?
Under-funded rotas fail predictably: the fifth person is cut in budget review, then every holiday is covered by overtime until people leave, and the vacancy makes the coverage gap permanent.
What values do I need to enter?
This calculator takes 7 inputs: Seats to staff concurrently, Coverage model, Contracted hours per FTE per week, Shrinkage — leave, sickness, training, attrition, Tier 2 analysts per tier 1 analyst, Analysts per team lead, Fully loaded cost per FTE. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.
Why is 4.2 the magic number?
A week has 168 hours and a full-time analyst works about 40, so covering one chair around the clock takes 4.2 people even if nobody is ever ill or on leave. Any rota built on four is quietly relying on overtime.
Can a managed service replace the fifth FTE?
Often, yes — and that is usually the honest comparison. Outsourcing nights and weekends buys the expensive part of the coverage curve, but only works if the provider has authority to contain, not just to notify.