How do you calculate probability-weighted OT downtime cost?

Multiply the outage units by the cost per unit by the likelihood share to get expected loss, then add the fixed readiness cost. Here 24 units times $18,000 times 12% is $51,840 of weighted exposure, plus $40,000 readiness equals $91,840 total.

What does the likelihood share represent?

It's your best estimate of the probability the scenario occurs in the period, expressed as a percent. The 12% here means you expect this specific OT downtime scenario roughly once every eight-ish years, which scales the full outage cost down to an expected value.

Why separate readiness cost from the weighted loss?

The weighted loss is what you expect to lose; the readiness cost is what you spend to keep that probability low. Showing them separately lets you argue that the $40,000 fixed spend is what holds the likelihood at 12% rather than higher.

What is a downtime scenario unit?

It's whatever you meter the outage in, commonly hours of lost production or lost production batches. With 24 units at $18,000 each, the model is treating the outage as 24 hours at $18,000 per hour of lost output and response.

How do I use this for a cyber-insurance decision?

Compare the total exposure, $91,840 here, and especially the weighted-loss portion against the annual premium. If the premium is well below your expected loss for covered scenarios, transferring the risk often makes sense.

Is a higher or lower total cost better?

Lower is better, but the goal is to lower the weighted-loss portion by reducing either the outage cost or its likelihood, not by cutting the fixed readiness spend that keeps the likelihood down in the first place.

Industrial Cybersecurity & OT Risk calculator

OT Cyber Downtime Probability Calculator

OT cyber downtime probability cost turns a hypothetical industrial cyber outage into a budget number by weighting the full outage cost by how likely the scenario actually is, then adding the fixed cost of staying ready. Plant managers, OT security leads, and risk officers use it to justify cyber spend in language finance understands, because an unweighted worst-case outage number is easy to dismiss as scaremongering. By separating the probability-weighted loss from the fixed readiness investment, the model shows both what an incident could cost on an expected-value basis and what you're already spending to lower that probability. This is the kind of figure that anchors a cyber-insurance conversation or a board-level request for segmentation funding.

What this calculator does

Estimate probability weighted OT cyber downtime exposure using downtime scenarios, cost per scenario, likelihood, and fixed readiness costs.
Use it when converting downtime scenarios into annualized risk exposure for leadership or investment reviews.
It computes a probability-weighted expected loss from an OT cyber outage and adds the fixed readiness cost to give a single total exposure figure.

Formula used

Probability weighted OT cyber downtime exposure = OT cyber downtime scenario units × cost per downtime scenario unit × expected likelihood or occurrence share
Total OT cyber downtime probability cost = probability weighted exposure + fixed readiness and risk review cost

Inputs explained

OT cyber downtime scenario units:
Cost per downtime scenario unit:
Expected likelihood or occurrence share:
Fixed readiness and risk review cost:

How to use the result

Use it when building a business case for cyber spend or sizing cyber-insurance coverage against expected annual loss.
It relies on a single point estimate of likelihood and assumes outage cost scales linearly with units, so it is a planning estimate rather than an actuarial figure.

Common questions

How do you calculate probability-weighted OT downtime cost? Multiply the outage units by the cost per unit by the likelihood share to get expected loss, then add the fixed readiness cost. Here 24 units times $18,000 times 12% is $51,840 of weighted exposure, plus $40,000 readiness equals $91,840 total.
What does the likelihood share represent? It's your best estimate of the probability the scenario occurs in the period, expressed as a percent. The 12% here means you expect this specific OT downtime scenario roughly once every eight-ish years, which scales the full outage cost down to an expected value.
Why separate readiness cost from the weighted loss? The weighted loss is what you expect to lose; the readiness cost is what you spend to keep that probability low. Showing them separately lets you argue that the $40,000 fixed spend is what holds the likelihood at 12% rather than higher.
What is a downtime scenario unit? It's whatever you meter the outage in, commonly hours of lost production or lost production batches. With 24 units at $18,000 each, the model is treating the outage as 24 hours at $18,000 per hour of lost output and response.
How do I use this for a cyber-insurance decision? Compare the total exposure, $91,840 here, and especially the weighted-loss portion against the annual premium. If the premium is well below your expected loss for covered scenarios, transferring the risk often makes sense.

Last reviewed 2026-05-12.