Inventory planning
Fill Rate
By the Supply Chain Manager team · Updated October 16, 2026
Fill rate is the share of customer demand shipped from stock on the first attempt, measured by units, order lines or whole orders.
It is the customer's view of availability. Unit fill rate counts units shipped against units ordered; line fill rate counts order lines shipped complete; order fill rate counts whole orders shipped complete, which is the strictest of the three.
Fill rate and service level are often confused. Cycle service level is a planning target about how often you run out during a replenishment cycle; fill rate measures how much demand you actually met. A business can hit a 95% cycle service level and still have a lower or higher fill rate, depending on how large the shortfalls are when they happen.
How to calculate fill rate
Unit Fill Rate = Units shipped from stock on first attempt ÷ Units ordered × 100
Fill rate example
Illustrative numbers: customers ordered 10,000 units across 1,000 lines in a month. 9,600 units shipped first time (96% unit fill rate), but 80 lines were short, so line fill rate is 92%. If those short lines were spread across 150 orders, order fill rate could be much lower again.
Why fill rate matters for distributors
Wholesale customers judge a distributor by whether orders arrive complete. Tracking fill rate by customer and SKU shows which stockouts actually hurt relationships.
Common fill rate mistakes
- Reporting unit fill rate when customers care about complete orders.
- Counting a short line as filled once a backorder ships later.
Examples on this page use made-up round numbers to show the calculation. They are not benchmarks or results from real businesses.