# How should a lab manage its reagent and consumable inventory?

> Why 50 vials on the shelf can be low stock: track by lot, keep on hand, reserved and available apart, use the first to expire, and reorder on available.

- Source: CCA Bio (Cell Culture Automation Ltd), Cambridge, UK
- Canonical URL: https://cca.bio/articles/lab-inventory-management
- Published: 2026-09-27
- Topic: Operations
- Tags: inventory, lab software, reagents, procurement, CCA Labs guide
- Series: One cell bank, from the budget to the bench and back (part 3 of 4)

## Short answer

Track reagents and consumables by lot, because expiry, QC status and location belong to the lot. Keep three numbers apart: on the shelf, reserved by scheduled work, and available. Use the lot that expires first, take stock off the count when the work starts, and reorder when available stock reaches a level set by usage and lead time.

Our example lab has 50 cryovials on the shelf, and CCA Labs says they're running low. It's right. A cell bank run scheduled for 17 September has already claimed 40 of them, and that's the most useful thing an inventory system can tell you.

I think of lab inventory as a control problem. There's a quantity, a sensor that reads it, a threshold that triggers an order, and a delay before the order lands. Read the wrong sensor, the shelf instead of what's left once planned work has taken its share, and the loop oscillates: six bottles of serum one month, none the next. This piece is about which numbers to keep, when stock should come off the count, and how we built that into CCA Labs.

## Why track inventory by lot and not just by product?

Because everything that goes wrong with stock goes wrong at the level of the lot. A product is "fetal bovine serum, 500 mL". A lot is the batch that actually arrived, with its own lot number, expiry, certificate of analysis and place on a shelf.

When the example lab's order arrives on 4 September, each line becomes a lot. The serum is `LOT-FBS-2607`, expiring July 2028, in the reagent freezer. The DMEM is `LOT-DM-2608`, expiring March 2027, in the cold room. One lot passes your in-house QC and the next one hasn't been tested. When a batch of serum behaves oddly, you need every experiment that used that batch. A record that only knows the product can't tell you any of it.

## What is the difference between on hand, reserved and available?

On hand is what's physically on the shelf. Reserved is what scheduled work has already claimed. Available is what's left: on hand, minus reserved, minus anything that failed QC. Only the last one tells you whether you can plan an experiment.

The cryovials show why. The bank run is scheduled, and scheduling reserves what each step will need against specific lots:

| Cryogenic vials, 2 mL | Count |
| --- | --- |
| On hand | `50` |
| Reserved for the bank run | `40` |
| **Available** | **`10`** |
| Low Stock Threshold | `20` |

Available is at or below the threshold, so the item shows **Low Stock** with 50 vials sitting in the store, ten days or more before the run uses them. That's when you want to know, because the lead time is still ahead of you. Plan a second bank off the shelf count and you'd find ten vials on the day.

It looks wrong the first time. It isn't. And if more has been planned than you hold, the item shows low with every bottle still on the shelf.

## Which lot should you use first?

The one that expires first, whichever arrived first. That's FEFO: first expired, first out.

First in, first out only works if every delivery has the same shelf life, and biological reagents rarely do. A lot that arrived in January with a year on it should wait for the one that arrived last week and expires next month. CCA Labs takes stock from lots in expiry order and never offers a lot that failed QC.

## When should stock come off the count?

When the step starts, because that's when the tube is opened and the stock physically leaves.

The two other options both put an error into the reading. Deduct at planning and the shelf reads low for weeks. Deduct at completion and it reads high for days, and a run that fails halfway never deducts anything. So CCA Labs splits it: scheduling reserves, and starting the step turns the reservation into a real deduction. When the bank's cryopreserve step starts on 17 September, 40 vials leave the count, with the 36 mL of serum and 4 mL of DMSO that make up the freezing medium. Afterwards, 10 vials are on hand and nothing is reserved.

A step that starts and then fails has still used what it opened. That's what happened at the bench, so it's what the record says.

## Stock that leaves without being used

Bottles break. Lots expire. A stocktake finds four boxes where the record says five. Each needs a reason, because they mean different things. A breakage is a loss someone should explain. Destroying an expired lot is a decision. A stocktake correction is the record catching up with the shelf.

CCA Labs has **Consume stock** for this, with four reasons: Process Loss, Spillage or Breakage, Expired or Rejected Material, and Stock Reconciliation. It can't take stock that scheduled work has reserved.

There's no "used at the bench" reason, on purpose. The point of tracking lots is being able to say which runs used which one, so every use goes through an experiment. A "used some" button would be the easiest path in the building, and the traceability would leak out through it. The price is that even a quick test needs an experiment record. We decided that's worth paying.

## What should happen to a lot that fails QC?

Keep it on the record and take it out of use. It's still on the shelf, so it's still on hand, but nobody should be able to pick it up by mistake.

Every lot in CCA Labs has a release state: QC released, QC failed or not required. A failed lot shows as quarantined, and every route that hands out stock refuses it, by name if anything asks. Disposal is a separate, recorded step. Deleting the lot would be a mistake: if a lot of media is suspected of causing a contamination, you want it out of new work and you want every experiment that already used it. Delete it and you've lost the second list.

## How do you know when to reorder?

Reorder when available stock, not the shelf count, falls to a reorder level: weekly use, times the supplier's lead time in weeks, plus a margin for busy weeks. In CCA Labs that level is the item's **Low Stock Threshold**.

Lead time is the delay in the loop, and it's the number most labs guess. CCA Labs measures it: the observed lead time is the median days from order to delivery over the item's last ten orders. I prefer a median for the same reason I'd keep outliers out of any sensor reading. One delivery stuck in customs for a month would skew an average until it dropped out of the last ten. It barely moves a median.

Expiry is the other trigger. Once a day, CCA Labs looks for lots with stock left that will expire within 15 days plus the item's lead time, and tells the lab, unless the item is already on order. Low items can be added to the order queue one at a time or all at once. A person still places the order, which is how the example lab's replacement vials go out on `PO-00004`. That side is in [what a lab purchase order process should look like](/articles/lab-purchase-order-process).

## What an inventory item looks like in CCA Labs

Open an item, say fetal bovine serum, and you get:

- **Stock level** over time, with the reorder level drawn across it.
- **Lots**, each with its lot number, quantity, expiry, storage location down to the shelf, cost and QC release state. Each lot can have its own QR label.
- **Reserved**: which scheduled experiments have claimed stock, and how much.
- **Procurement details**: supplier, catalogue number, average cost and observed lead time.
- **Usage and activity**: monthly use and loss, which workflows use the item, and every movement.

Counted and measured stock are kept apart. Vials and plates have whole-number quantities, because 2.7 plates isn't a thing. Media can be fractional and entered in any unit of the same kind, so you receive in litres and use in millilitres, with the unit on the box kept beside the converted value.

You don't need to retype your stock sheet. When you [create your lab](https://lab.cca.bio/), upload it and the AI drafts inventory items in minutes. The drafts wait under **AI Drafts** until someone on your team checks them and chooses **Promote**. The freezer works the same way ([why the freezer spreadsheet always drifts](/articles/freezer-inventory-spreadsheet-fails)), and the rest is on the [all-in-one lab page](/all-in-one-lab#operations).

Forty of those cryovials don't stay inventory for long. On 17 September they're filled with cells and become samples, each with its own ID, history and place in a dewar. That's a different kind of record, and the next part of the story: [how to track a lab sample from the vial to the result](/articles/sample-tracking-vial-to-result).

## Part of: One cell bank, from the budget to the bench and back

One example project, followed through a lab: a working bank of HEK293 cells. The lead funds it, operations orders and stocks what it needs, the bench runs it and banks 40 vials, and the cost comes back up to the project the lead funded. Each part is written for the people on that floor.

- [What is all-in-one lab management software, and what should it cover?](https://cca.bio/articles/all-in-one-lab-management-software) (Overview)
- [How do you track a lab budget across several grants and projects?](https://cca.bio/articles/lab-budget-tracking) (Leadership, for lab leads, PIs and whoever holds the grants)
- [What should a purchase order process look like in a research lab?](https://cca.bio/articles/lab-purchase-order-process) (Operations, for lab managers and whoever places the orders)
- (this article) [How should a lab manage its reagent and consumable inventory?](https://cca.bio/articles/lab-inventory-management) (Operations, for lab managers and whoever keeps the shelves)
- [How do you track a lab sample from the vial to the result?](https://cca.bio/articles/sample-tracking-vial-to-result) (Lab, for scientists at the bench, and QA)

## Frequently asked questions

### What is FEFO in lab inventory?

First expired, first out: when you take stock, use the lot with the earliest expiry date, whichever arrived first. It wastes less than first in, first out, because a late delivery with a short shelf life gets used before it expires.

### What is the difference between inventory and samples?

Inventory is what you buy and use up: reagents, media, kits and consumables, tracked by lot. Samples are material you make or receive to study, such as cell stocks, aliquots and extracts, each with its own ID, history and chain of custody. CCA Labs keeps them in separate registries that link to each other.

### How do you set a reorder level for a reagent?

Take how much you use in a typical week, multiply by the supplier's lead time in weeks, and add a margin for busy weeks. Reorder when the available stock, after reservations, falls to that level, not when the shelf looks empty.

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Cite as: CCA Bio. "How should a lab manage its reagent and consumable inventory?". 2026-09-27. https://cca.bio/articles/lab-inventory-management