Fill rate measures how much requested demand is fulfilled under a defined rule. A unit fill rate counts units; a line fill rate counts complete order lines; an order fill rate counts complete orders. Always state the denominator and whether “filled” means immediately from stock, on the first shipment or by an agreed date.
Unit, line and order fill rate
Unit fill rate = units fulfilled under the rule / units requested × 100
Line fill rate = complete lines under the rule / lines requested × 100
Order fill rate = complete orders under the rule / orders requested × 100
An illustrative order contains two lines: 50 units of A and 50 of B. The supplier delivers all 50 of A and 40 of B in the first shipment.
- Unit fill rate: 90 / 100 = 90%.
- Complete-line fill rate: 1 / 2 = 50%.
- Complete-order fill rate: 0 / 1 = 0%.
The same delivery legitimately produces three different percentages. If the missing ten arrive later, the eventual fill rate can be 100% while the first-shipment rate remains 90%.
Fill rate is not cycle service level
Cycle service level is the probability that a replenishment cycle has no stockout under the model or measurement rule. Fill rate is the share of demand served. There is no universal conversion such as “95% cycle service means 99% fill rate.” Order size, demand distribution, lead time and shortage size matter.
For example, if 251 of 270 requested units are immediately available, observed unit fill rate is 251 / 270 = 92.96%. That observation does not establish the annual fill rate or the probability of a stockout in future cycles.
Select targets from customer commitments, criticality and the cost of shortages and stock. ABC value alone does not determine an appropriate target: a low-cost component may block an entire service or production run.
Measure the right demand
Supplier fill rate usually starts with units requested on the buyer's orders. Customer fill rate may require requested-but-unavailable demand that completed sales do not capture. Distinguish observed demand from estimated lost demand; do not report an estimate as measured sales.
Preserve the original request and any accepted revision. If a supplier reduces a confirmed quantity, measuring only against that reduced figure can hide the shortfall against the customer's original need. Track substitutions and cancellations under an explicit rule instead of changing the denominator silently.
Aggregate unit fill rate from total fulfilled units divided by total requested units. An unweighted average of order percentages can overstate the influence of tiny orders. Review important SKUs and suppliers separately as well as the aggregate.
Connect the metric to purchasing
LineNow's purchase-order tracking keeps supplier replies and receipts attached to the order. Those records can support fill-rate analysis when requested, confirmed and received quantities remain distinct. Confirm the reporting rule and export fields in a trial; do not assume a particular dashboard or automatic lost-demand estimate.
If shortages recur, review delivery dates, pack sizes and unresolved balances before adding safety stock or opening a second order. Compare timing as well as quantity with on-time in-full.