Laboratory Inventory Control Fundamentals

Laboratory inventory control is the set of practices used to know what materials are held in a laboratory, where they are located, in what quantity, and in what condition. An inventory system tracks material from the point of receipt through storage and use to exhaustion or disposal. Maintaining an accurate inventory reduces the risk of using incorrect material, running out of stock unexpectedly, or retaining material past its usable period. The overview below is factual and educational; it describes general inventory principles and contains no guidance on the use of any material.

At minimum, an inventory record for a research material includes the material name, batch or lot number, quantity received and quantity remaining, storage location, date of receipt, and any expiry or retest date provided. Where multiple batches of the same material are held, each batch has its own inventory entry so that the records remain unambiguous. Additional fields such as supplier reference, cost centre, or intended project may be included depending on the laboratory’s administrative requirements.

The inventory record is updated whenever material is received, used, transferred, or disposed of. Keeping it current in near real time is more reliable than attempting periodic reconstruction from memory or secondary sources, since small quantities used across many sessions are easily overlooked in retrospective recording.

Inventory can be managed in paper records, spreadsheets, or dedicated laboratory information management systems (LIMS). Each approach has trade-offs in terms of accessibility, version control, and the ease of searching and reporting. Regardless of format, the same principles apply: records must be kept current, accessible to those who need them, and protected against accidental loss. For guidance on keeping records in a usable form over time, see Laboratory Record Keeping Best Practices.

First in, first out (FIFO)

The first-in, first-out (FIFO) principle means that the oldest material in stock is used before newer stock of the same material. This is achieved by storing older stock at the front of the storage area, or by ensuring that older material is identified and selected first. FIFO helps prevent older material from remaining in storage while newer deliveries are used, which could result in older material eventually being discarded without having been used.

First expired, first out (FEFO)

The first-expired, first-out (FEFO) principle extends FIFO by prioritising the material with the earliest expiry or retest date, regardless of receipt order. Where materials have stated expiry or retest dates, FEFO ensures that material approaching the end of its stated period is used before material with a later date. This is particularly relevant when different batches of the same material are held simultaneously.

A cycle count is a periodic count of a subset of inventory items, conducted on a rolling basis so that each item is counted at regular intervals over time. Cycle counting is less disruptive than a full physical inventory conducted at a single point in time, and it allows discrepancies to be identified and investigated promptly rather than accumulating until an annual count. Full physical inventory, in which all items are counted simultaneously, may be conducted periodically to reconcile the entire inventory record.

A discrepancy is a difference between the quantity recorded in the inventory and the quantity found during a physical count. Discrepancies can arise from recording errors, unreported use, spillage, labelling confusion, or theft. When a discrepancy is found, it should be investigated to determine its cause before adjusting the record. The investigation and its conclusion should be documented, even where the cause cannot be determined with certainty. Repeating discrepancies may indicate a systemic issue in recording practice or handling.

Good inventory control supports both day-to-day research operations and the broader goals of traceability and lifecycle management. For the lifecycle perspective on material from receipt through disposal, see Research Material Lifecycle Management. For receiving procedures that begin the inventory record correctly, see Research Material Receiving Procedures. Where materials are transferred between individuals or locations, those transfers are part of the chain of custody; for how transfer events are documented, see Chain of Custody in Research Environments.