How is the risk score weighted?

Criticality is 40%, supply availability risk 35% and lead-time and stocking exposure 25%. At 8, 6 and 5 the contributions are 3.2, 2.1 and 1.25, for a score of 6.55. The weights are stated, not hidden.

Why contributions instead of restating scores?

Restating an entered score adds no information. Each contribution row multiplies a score by its weight, so the largest row shows which factor drives the ranking and where a mitigation effort pays off.

Is the score a probability of failure?

No. It is a relative ranking convention for one catalog on one scale. Two parts are comparable only when both were scored with the same definitions and the same 0 to 10 scale.

What score should trigger a last-time buy?

No source sets a threshold, so the page does not invent one. Rank the parts and compare each against its own supply position; treat the top of the distribution as the candidate set and confirm with engineering judgment.

Nuclear & Critical Infrastructure Manufacturing calculator

Spare Part Obsolescence Risk Calculator

Rank spare parts for obsolescence action on one weighted score. Enter criticality, supply availability risk and lead-time exposure on the same 0 to 10 scale, and the page shows what each factor contributes.

What this calculator does

Weighted ranking score for spare-part obsolescence risk, with each factor's contribution shown.

Formula used

Obsolescence risk score = 0.40 × criticality + 0.35 × supply risk + 0.25 × lead-time exposure
Criticality contribution = criticality score × 0.40
Supply risk contribution = supply risk score × 0.35
Lead-time contribution = lead-time exposure score × 0.25
Rank parts on the same 0 to 10 scale before comparing scores

Inputs explained

Component Criticality Score: Safety and operational importance on a shared 0 to 10 scale.
Supply Availability Risk Score: Sourcing fragility from supplier health and single-source status.
Lead-Time and Stocking Exposure Score: Replacement lead time against the stock cover on hand.

How to use the result

Best suited to triaging a spares catalog before a budget cycle, comparing a relay, motor and valve spare.
A weighted score ranks parts; it does not set a threshold for action. Scores age quickly after a supplier, market or stock position changes.

Common questions

How is the risk score weighted? Criticality is 40%, supply availability risk 35% and lead-time and stocking exposure 25%. At 8, 6 and 5 the contributions are 3.2, 2.1 and 1.25, for a score of 6.55. The weights are stated, not hidden.
Why contributions instead of restating scores? Restating an entered score adds no information. Each contribution row multiplies a score by its weight, so the largest row shows which factor drives the ranking and where a mitigation effort pays off.
Is the score a probability of failure? No. It is a relative ranking convention for one catalog on one scale. Two parts are comparable only when both were scored with the same definitions and the same 0 to 10 scale.
What score should trigger a last-time buy? No source sets a threshold, so the page does not invent one. Rank the parts and compare each against its own supply position; treat the top of the distribution as the candidate set and confirm with engineering judgment.

Last reviewed 2026-10-01.