Industrial Cybersecurity & OT Risk calculator

Patch Compliance Rate Calculator

Use this calculator to measure patch compliance for OT assets that are eligible for approved patching. It supports risk based patch reviews where production windows, vendor certification, and validation constraints matter.

What this calculator does

  • Calculate OT patch compliance using patched assets, eligible assets, and target patch compliance.
  • Use it when reviewing patch backlog across HMIs, servers, engineering workstations, historians, and vendor supported OT endpoints.
  • The result shows OT patch compliance and the point gap to the target.

Formula used

  • Patch compliance rate = OT assets patched to approved baseline ÷ total OT assets eligible for patching × 100
  • Patch compliance gap to target = patch compliance rate - target patch compliance

Inputs explained

  • OT assets patched to approved baseline: Count assets with approved operating system, application, firmware, or security updates applied and validated.
  • Total OT assets eligible for patching: Use the matching population after excluding assets under vendor hold, compensating controls, or approved deferral.
  • Target patch compliance: Enter the compliance goal from policy, audit requirement, risk treatment plan, or maintenance standard.

How to use the result

  • Use it to plan maintenance windows, compensating controls, vendor coordination, and remediation reporting.
  • It should not encourage unsafe patching. OT patches still require testing, approval, backups, and rollback planning.

Common questions

  • What is the patch compliance rate calculator for? It calculates how much of the eligible OT asset population is patched to an approved baseline.
  • What information should I enter? Use patched eligible assets, total eligible assets, and target compliance rate.
  • What does the result tell me? The result helps plan patch windows and communicate backlog risk.
  • When is the result only an estimate? It is only an estimate when eligibility, approved baselines, vendor holds, or validation status are not current.

Last reviewed 2026-05-12.