Written and maintained by CASRAI Editorial Board
Last updated
General information for supply and inventory staff. It is not medical advice and not a procedure. Sources checked 2026-11-01.
Short answer
A par level is the quantity of a supply a storage location is meant to hold, and a par level system is a replenishment routine that restocks that location back toward it. The word is used in more than one way in the literature, so before you change a par you need to know whether it means a target, a trigger or a quantity. Studies of hospital stock show that resetting pars can lower or raise stockouts, so the new numbers need checking against what actually happens.
Definition and scope: what “par level” means in a supply room
For a formula and a worked calculation, see the CASRAI entry on par level in clinical supply management. This page asks a different question: which replenishment system is a par level, and what do published studies say about setting and reviewing one?
Par level meaning
Peer-reviewed papers use “par level” for the quantity a location is restocked to, and one operations paper treats a par-level policy as the same thing as a periodic-review, base-stock policy (Source 1).
Par level system
A par level system is one of several named ways of distributing supplies to the point of use. A 1994 article in Hospital Materiel Management Quarterly compares exchange cart, par level and just-in-time distribution systems as separate options for material managers (Source 2). The abstract states only that they are different systems; it does not rank them.
How “par” is used in the sources
The sources do not use “par” identically.
| Use of “par” | What the source says | Source |
|---|---|---|
| Order-up-to level | Assumes “a periodic-review, base-stock (or par-level) inventory policy”; the models look for “the optimal order-up-to level”. | Source 1 (hospital point-of-use supplies) |
| Desired on-hand quantity | Par levels are “desired accessible quantities” (2024) or “desired on-hand quantities” (2016) of medications. | Sources 4 and 5 (medications in automated dispensing cabinets) |
| Separate reorder quantity | Refers to “par inventory levels” and, separately, “par reorder quantities”. | Source 5 |
Two readings follow from the table, and both are editorial interpretation. A conversation about “the par” can mean the target, the quantity ordered, or both. A supply-room review should say which one it is changing.
Par level vs reorder point, exchange cart and just-in-time
Source 2 names exchange cart, par level and just-in-time as distinct distribution systems and says nothing more in its abstract. For the relationship between a reorder point and a par, use the CASRAI par level entry. For related buffering ideas, see safety stock vs buffer stock and kanban inventory.
How pars are set and reviewed in studies
Counting frequency and usage capture are choices too
The 2022 paper in Health Care Management Science (Source 1) models a par-level policy at a point-of-use location. It asks two questions: what order-up-to level is best, and how often to count stock to reconcile inaccurate records. The authors state that recording demand with perfect, 100% accuracy is infeasible. A par is therefore only as good as the usage data and the counts behind it.
Resetting pars can help or hurt
Two pharmacy studies measured what happened after pars were changed (the 2016 project also expanded stocked items and removed rarely used ones, so the result is not from pars alone). Both involve medications in automated dispensing cabinets, not general supplies, so they show the pattern rather than a supply-room result.
- McCarthy and Ferker (2016, Source 5) report that weekly stockouts fell from 3.2% before optimization to 0.5% eight months later, across 30 units.
- Walczyk et al. (2024, Source 4) compared two ways of recalculating pars in 10 cabinets over 2 months, one based on economic order quantity and one on historical average daily usage. Stockouts rose and the vend-to-fill ratio fell in both groups. Expired quantity rose in the first group and fell in the second. Carrying cost fell by US$11,011. The adjustments also removed items unused for 90 or more days.
A third article, from 1994, reports that statistical methods applied to par-level management gave “significant results” (Source 3). The abstract gives no figures.
Where it matters for labs, clinics and supply decisions
These checks come from the sources above and are not a validated protocol.
- Say whether “par” means the target on-hand quantity, the order quantity, or both (Source 5).
- Check how usage is recorded at the location, because recording is imperfect (Source 1).
- Decide how often stock is counted, because count frequency is a policy variable (Source 1).
- After a change, look at both stockouts and expired or unused stock (Sources 4 and 5).
For the wider context, see medical supply inventory management, healthcare inventory management, stockouts and obsolete medical supply inventory. For drug stock in dispensing cabinets, see par levels in pharmacy.
Common misunderstandings
- “Par” is one fixed number. The studies above treat it as a quantity to be recalculated and reviewed.
- Par is the same as the amount you order. Source 5 names par reorder quantities separately from par levels.
- A recalculation always reduces stockouts. In Source 4 stockouts rose in both groups; in Source 5 they fell.
- A par level system is the same as an exchange cart. Source 2 lists them as different systems.
FAQ
What is the par level meaning in medical supplies?
It is the quantity of an item a storage location is meant to hold. Research papers use par level for the order-up-to quantity.
What is a par level system?
It is a periodic replenishment routine that restocks a location toward its par. It is named alongside exchange cart and just-in-time systems as a distinct way of distributing supplies (Source 2).
What is the difference between a par level and a reorder point?
Source 5 distinguishes “par inventory levels” from “par reorder quantities”, which shows the terms are not interchangeable. The CASRAI entry on par level covers par versus reorder point in detail.
How is a par level system used in a hospital supply room?
Many US hospital supply chains use a “stockless” structure with point-of-use locations (Source 1). Each location has a quantity it is restocked to, and the quality of its usage records and counts affects how well that works.
Sources
- Point-of-use hospital inventory management with inaccurate usage capture. Health Care Management Science, 2022. PubMed 34355302, DOI 10.1007/s10729-021-09573-1. Checked 2026-11-01.
- Exchange cart and par level supply distribution systems: form follows function. Hospital Materiel Management Quarterly, 1994. PubMed 10131700. Checked 2026-11-01.
- The use of statistical techniques in par-level management. Hospital Materiel Management Quarterly, 1994. PubMed 10131693. Checked 2026-11-01.
- Walczyk et al. Hospital Pharmacy, 2024. PubMed 38764986, DOI 10.1177/00185787231214416. Checked 2026-11-01.
- McCarthy and Ferker. American Journal of Health-System Pharmacy, 2016. PubMed 27646814, DOI 10.2146/ajhp150531. Checked 2026-11-01.
