Reorder point = daily usage x (lead time + safety days). For example, 6 jobs a week (about 0.86 a day) with a 3-day lead time and 2 safety days gives a reorder point of 5. With no minimum order quantity, as at Parts4Cells, you can top up exactly to the calculated level.
How does the calculation work?
- Daily usage = weekly jobs / 7
- Reorder point = daily usage x (lead time + safety days), rounded up
- Order-up-to level = daily usage x (lead time + safety days + days between orders), rounded up
Which parts should you plan this way?
Your top ten parts by jobs, usually screens and batteries for your most common iPhone and Galaxy models, plus charging ports. Everything else can be ordered per job.
How do real-time stock and lead time interact?
Lead time is only reliable if the part was in stock when you ordered. A supplier that shows real-time stock lets you trust your lead time. Check new arrivals weekly for models that are just starting to come in: new arrivals.
What about batteries on the shelf?
Lithium batteries age in storage and are hazardous materials. Keep battery stock lean, store it cool and away from metal objects, and rotate older stock first.
Sources
Sources checked September 29, 2026. Prices, stock and program terms change; confirm them on the linked pages.