Safety stock keeps orders moving when deliveries don't Most safety stock calculations assume your lead time data is telling the truth. It isn't. If you've been in replenishment for more than a year, you already know this. The number in your system is whatever someone typed in during setup, maybe updated once, and now it sits there like a fact while your actual supplier delivers anywhere from 6 to 14 days depending on the week, the carrier, the weather, and what else is going