How do you calculate spare-parts obsolescence exposure?

Multiply parts at risk per review by the number of review cycles to get gross risk, then multiply by still-salable share and recoverable disposition yield. Here, 85 x 6 = 510 gross, and 510 x 70% x 55% = about 196 recoverable parts.

What is the difference between gross risk and recoverable exposure?

Gross risk (510 parts) is everything flagged at risk across the cycles. Recoverable exposure (196.35 parts) is what you can actually monetize after removing unsalable stock and disposition losses.

What happens to the parts that are not recoverable?

Of the 510 gross at-risk parts, 153 are no longer salable and 160.65 are lost to disposition yield. Those roughly 314 units are your write-off or scrap exposure.

What is a good still-salable stock share?

It depends on product lifecycle, but 60-80% is typical for parts caught early in obsolescence. A 70% salable share, as modeled here, is reasonable; it falls fast once equipment is fully retired.

How can I improve recoverable disposition yield?

Sell earlier through secondary markets, offer last-time-buy programs to customers, refurbish where economical, and build broker relationships. Lifting yield from 55% toward 70% on this example would recover roughly 53 more parts.

How often should I run obsolescence reviews?

Quarterly is common for active service portfolios. The review-cycle input lets you model annualized exposure; six cycles here represents a part of the catalog reviewed on a recurring basis.

Aftermarket, Field Service & Service Parts calculator

Spare Parts Obsolescence Exposure Calculator

Spare-parts obsolescence exposure measures how many at-risk service parts you can realistically recover through resale, repair, or alternative disposition before they become write-offs. Aftermarket inventory planners and service-parts managers use it because obsolescence is a silent margin killer: parts for end-of-life equipment accumulate quietly until a year-end write-down exposes them. By modeling the still-salable share and the yield you actually capture on disposition, this calculator turns a vague risk into a recoverable-unit number you can plan against. It is the bridge between an obsolescence review and a concrete recovery target.

What this calculator does

Estimate obsolete spare parts exposure from parts at risk per review cycle, review cycles, salable share, and recoverable disposition yield.
a parts inventory analyst needs to estimate how many spare parts may become obsolete or need disposition
It computes gross parts at obsolescence risk across review cycles and the subset you can recover after applying still-salable share and disposition yield.

Formula used

Gross obsolescence risk = parts at risk per review × inventory review cycles
Recoverable exposure = gross risk × still-salable share × recoverable disposition yield

Inputs explained

Parts at obsolescence risk per review:
Inventory review cycles:
Still-salable stock share:
Recoverable disposition yield:

How to use the result

Use it during periodic inventory reviews or annual obsolescence provisioning to size your recovery opportunity versus your write-off exposure.
It assumes the salable share and disposition yield hold steady; in practice, the longer parts age, the lower both percentages tend to fall.

Common questions

How do you calculate spare-parts obsolescence exposure? Multiply parts at risk per review by the number of review cycles to get gross risk, then multiply by still-salable share and recoverable disposition yield. Here, 85 x 6 = 510 gross, and 510 x 70% x 55% = about 196 recoverable parts.
What is the difference between gross risk and recoverable exposure? Gross risk (510 parts) is everything flagged at risk across the cycles. Recoverable exposure (196.35 parts) is what you can actually monetize after removing unsalable stock and disposition losses.
What happens to the parts that are not recoverable? Of the 510 gross at-risk parts, 153 are no longer salable and 160.65 are lost to disposition yield. Those roughly 314 units are your write-off or scrap exposure.
What is a good still-salable stock share? It depends on product lifecycle, but 60-80% is typical for parts caught early in obsolescence. A 70% salable share, as modeled here, is reasonable; it falls fast once equipment is fully retired.
How can I improve recoverable disposition yield? Sell earlier through secondary markets, offer last-time-buy programs to customers, refurbish where economical, and build broker relationships. Lifting yield from 55% toward 70% on this example would recover roughly 53 more parts.

Last reviewed 2026-05-12.