Fill rate is the share of orders (or order lines) shipped complete from on-hand stock, with no backorder, no split shipment, and no substitution. A 95% fill rate means 1 in 20 orders couldn’t be filled cleanly from what was available.
What It Actually Tells You
A low fill rate is usually a stock problem in disguise. The 3PL can’t ship what isn’t on the shelf, or what the system doesn’t know is on the shelf. So fill rate leans heavily on inventory accuracy. When counts are wrong, orders fail to fill even though the product is physically there.
How Brands See It
Your 3PL tracks fill rate internally. You feel it indirectly: backorder notices, split-shipment costs, and “where’s the rest of my order?” tickets. It’s the “in-full” half of OTIF. Watching fill rate next to your on-time numbers tells you whether a bad week was slow or short.