Shelf-Life Material Expiry Write-Off Calculator (Sealants, Adhesives, Prepreg)
Sealants, adhesives, prepreg, films and some paints carry a hard expiry. Buy too much and the surplus is scrapped; buy too little and the line stops. This calculator finds the largest order that will be used before expiry and prices what happens when you order more.
Your numbers
Supplier delivers with this share of the shelf life left.
Material below this is not allowed on the part.
Your results
Assumes constant consumption and FEFO issue. Real demand is lumpy, so treat results as a planning guide and confirm limits against the material specification and your shelf-life extension procedure.
Annual write-off vs order quantity
Sweeps Order quantity from 100 to 2400, holding your other inputs fixed.
Expiry-aware purchasing
Optional: we can review how lot expiry and demand data could drive purchase quantities in your ERP.
Optional. The tool and every export work without this. No spam.
How to use it
Enter annual usage and unit cost, the full shelf life, the share of life left on delivery, and the minimum life the process allows at point of use. Then try different order quantities. The result is the safe quantity, the expired units per order, and the yearly write-off. The chart sweeps order size so you can see where waste starts.
- Use cold-storage out-time limits separately, they are not shelf life.
- Update the remaining-life percentage from real receipt data.
- Re-run for each material, they behave very differently.
The method
Usable months equal total life times the share remaining on receipt, minus the minimum life at use. Safe quantity is monthly usage times usable months. Anything above it expires before it can be consumed, and annual write-off is the number of orders per year times the expired units times unit cost. The model is intentionally simple so it can be checked by hand.
ERP notes
Most ERPs track lot expiry dates and can issue by earliest expiry, but few warn when a purchase order quantity exceeds what demand can consume. Check planning parameters such as lot size, minimum remaining shelf life on goods receipt and the expiry-date fields on lot records. Freezer-controlled materials also need a record of thaw time and out-time.
Frequently Asked Questions
Does this model uneven demand?
No. It assumes steady monthly use. For lumpy demand, run the tool with a conservative usage figure or use the forecast for the next shelf-life window instead of annual average usage.
What is minimum remaining shelf life?
It is the least life a lot may have left when issued or received. Many sites use it as an acceptance rule at goods receipt, which stops short-dated material entering stock.
Can expired material be extended?
Sometimes, under a documented shelf-life extension program with retest data and customer or material specification approval. Never extend without that authority; the calculator treats expiry as final.
Why does a bigger order cost more here?
Because once the order exceeds what you can use in the usable window, the excess expires. Bigger orders may still win on unit price, so compare the write-off with the discount you are offered.
If you want expiry risk flagged at purchase order time from live demand in your ERP, we can scope that with you.
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