Key takeaways
- Fill rate measures demand met from stock on hand.
- It can be measured by order, line, or unit, each stricter than the last.
- It trades off against inventory: higher fill usually needs more stock.
- Better forecasting and optimization raise fill without just adding stock.
How is fill rate measured and improved?
Fill rate divides what was shipped from stock by what was demanded, without backorders. Order fill rate is strictest (the whole order must be complete), line fill rate looks at each line, and unit fill rate at quantities. Which one you use changes the number, so the definition must be agreed with the customer.
The naive way to raise fill rate is to hold more stock everywhere, which is expensive. The efficient way is better demand forecasting and inventory optimization, so the right stock sits in the right place. InfoSun lifts fill rate by improving the plan, not just the buffer.
Why fill rate matters
- It is a direct measure of whether customers get what they ordered.
- It underpins OTIF and the customer relationship.
- Managed well, it improves service without ballooning inventory.
- It exposes where forecasting or stock placement is weak.
Fill rate in a 3PL and logistics operation
A 3PL tracking line fill rate by client finds a category consistently short despite high overall inventory: the stock is in the wrong locations. Re-forecasting and reoptimizing where inventory sits raises fill rate on that category while total stock actually falls, because the buffers move to where demand is.
Frequently asked questions
What is the difference between fill rate and OTIF?+
Fill rate measures how much of demand is met from stock without a stockout. OTIF (on-time in-full) measures whether deliveries arrive both on time and complete. Fill rate is about stock availability; OTIF adds the timing of delivery. An order can be filled from stock yet still miss OTIF if it arrives late.
Is a 100% fill rate the goal?+
Rarely. Pushing fill rate to 100% usually requires holding far too much inventory for the last few percent of demand. The goal is the fill rate that meets customer commitments at an acceptable inventory cost, which is an optimization, not a maximization.
Written and reviewed by the InfoSun operations team. Last updated July 13, 2026.