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Short answer: fill rate is the share of what was ordered that was actually supplied, usually counted in order lines, items or quantities. In health supply chains the name covers at least three measures with different denominators: a distributor’s first-attempt fill of purchase order lines, a warehouse’s in-full fill of internal requisitions, and a supplier’s fill of an order against its PO or contract.
Definition and scope
The USAID | DELIVER PROJECT guide to supply chain key performance indicators defines order fill rate as a measure of “the percentage of items ordered that are actually received to determine whether an order is filled in the correct quantities with the correct products.” It can be applied to individual products (a line fill rate) or to an entire order. Its formula is 1 – (quantity and type ordered – quantity and type received) / (total quantity and type ordered), multiplied by 100 (USAID | DELIVER PROJECT, 2010).
The American Hospital Association’s AHRMM publishes two fill measures among its Keys for Supply Chain Excellence, which it describes as key performance indicators that set the standard for supply chain management in health care (AHRMM Keys). Because each source counts something different, a fill rate figure is only meaningful once you know which version produced it.
How it is measured in practice
Primary distributor fill percentage (AHRMM)
AHRMM’s purpose statement is to measure the primary distributor fill rate, “represented as a percentage of packages or stock-keeping units (SKU) successfully shipped on the first attempt.” The equation is the number of purchase order lines filled on the first attempt by the primary distributor divided by the total number of PO lines submitted to it. AHRMM’s example is 10,000 PO lines submitted and 9,500 filled, which gives 95 percent, and it notes that a higher value is better. Organisations with a “Fill or Kill” program tabulate that month’s lines; those without one tabulate as required, for example daily or weekly. Purchase orders to suppliers that are not EDI capable are excluded (AHRMM, Primary Distributor Fill Percentage Rate).
Internal requisition and order fill percentage (AHRMM)
This key “measures the warehouse performance of order lines filled.” The numerator is internal requisition order lines filled in full and the denominator is total internal requisition lines ordered; lines that are only partially filled are left out of the numerator. It covers orders that departments place with the warehouse (AHRMM names ParEx and Pyxis as examples) and excludes orders sent directly to the supplier. AHRMM’s example is 2,000 lines received in the month with 1,850 filled in full, or 92.5 percent. AHRMM says supply chain should aim for a fill rate between 93 and 98 percent, and that for order lines not filled three days in a row on a three-day inventory on-hand PAR level, a stockout will be inevitable. It also states the measure is meant to monitor internal back-order rates, with a significant effect on supply chain’s relationship with end users and clinical staff (AHRMM, Internal Requisition and Order Fill Percentage Rate).
Supplier fill rate (USAID | DELIVER)
The USAID guide defines supplier fill rate as a measure of “a supplier’s ability to fill orders completely in terms of items and quantity, as defined in the PO/contract, during a definite period of time.” Its formula is the number of order lines, SKUs or cases shipped in the initial shipment divided by the total quantity ordered, times 100. Agreements may allow an order to be split into several shipments received in full by a set date, or may permit substitutes, and the guide says any such agreements should be considered. It adds that shipments should always be checked against the shipping notice and the PO, because what was shipped may not be what was ordered (USAID | DELIVER PROJECT, 2010).
Types: the same name with different denominators
The table below sets the three measures side by side. Every cell comes from the sources named in the column headers.
| Question | AHRMM primary distributor fill | AHRMM internal requisition fill | USAID | DELIVER supplier fill |
|---|---|---|---|
| What is counted | PO lines filled on the first attempt | Internal requisition lines filled in full | Order lines, SKUs or cases shipped in the initial shipment, against the PO or contract |
| What is left out | POs to suppliers that are not EDI capable | Partially filled lines (not in the numerator); orders sent directly to the supplier | No exclusions are listed in the formula; agreed split shipments and substitutes are to be considered |
| Who it grades | The primary distributor | The health system’s own warehouse | The supplier |
| Worked example in the source | 9,500 of 10,000 lines = 95% | 1,850 of 2,000 lines = 92.5% | No worked example given |
The USAID guide also describes order fill rate as usable for individual products (line fill rate) or for an entire order, and lists two related indicators: the percentage of facilities in a region whose orders are completely filled each order period, and the percentage of all orders accurately and completely filled out of all orders placed in a period (USAID | DELIVER PROJECT, 2010).
Where it matters for labs, clinics and supply decisions
A partial fill counts as a miss in the internal AHRMM measure, so a warehouse that ships most of a requisition can still post a low rate. That is deliberate: AHRMM ties repeated unfilled lines at a PAR level directly to stockouts, so a falling fill rate is an early signal before shelves are empty. For the stock-side concepts, see stockout, par level inventory and safety stock vs buffer stock.
The USAID guide says order fill rate “may reflect on issues in inventory management, picking, and shipping procedures,” and is used to judge how effective a distributing or shipping facility is. A low figure therefore does not by itself identify the supplier as the cause. For suppliers that are routinely noncompliant, the guide suggests identifying which items cause the most problems and finding another mechanism for those items, which is an item-level breakdown rather than a single blended rate. Related supply routes are covered in central stores, cross-docking and drop shipping vs direct stocking.
Common misunderstandings
- “Fill rate is one standard number.” The sources above use different numerators, denominators and exclusions. Compare figures only when the definition matches.
- “A partial shipment counts as filled.” In the AHRMM internal measure, partially filled lines are excluded from the numerator.
- “A low fill rate means a bad supplier.” The USAID guide says the result can reflect inventory management, picking and shipping practice as well.
- “Fill rate and stockout rate are the same thing.” Fill rate grades orders or lines against what was requested. The stockout rate indicator from Data for Impact is the number of service delivery points stocked out of a tracer product in a period, divided by the number reporting or visited, times 100, calculated per product (Data for Impact).
FAQ
What is a good fill rate?
For the AHRMM internal requisition and order fill percentage, AHRMM says supply chain should aim for a fill rate between 93 and 98 percent. That aim belongs to that internal warehouse measure and should not be applied to a distributor or supplier measure without checking its definition.
How do you calculate fill rate?
Divide the lines (or items, or quantity) filled by the lines ordered, using the counting rule of the measure you are reporting. In AHRMM’s distributor example, 9,500 filled lines out of 10,000 submitted is 95 percent.
What is the difference between fill rate and stockout?
Fill rate looks at how completely requests were met. Stockout rate looks at how many service delivery points had none of a tracer product during a period. A run of unfilled lines against a PAR level can lead to the second, as AHRMM notes.
Sources
- AHRMM, Primary Distributor Fill Percentage Rate (checked 2026-10-29)
- AHRMM, Internal Requisition and Order Fill Percentage Rate (checked 2026-10-29)
- AHRMM, Keys for Supply Chain Excellence (checked 2026-10-29)
- USAID | DELIVER PROJECT, Measuring Supply Chain Performance: Guide to Key Performance Indicators for Public Health Managers, May 2010 (checked 2026-10-29)
- Data for Impact, Stockout rate at service delivery points (checked 2026-10-29)
