Inventory Control Guide for SMBs

Inventory is the largest and most mismanaged asset in most SMBs. Too much stock means money sleeping on shelves, expiration risk, and storage costs eating into margins. Too little stock means lost sales, frustrated customers, and opportunities going to competitors. The sweet spot exists, and finding it does not require a sophisticated system — it requires understanding a few key concepts and applying them with discipline.

The Hidden Cost of Inventory

Most business owners see inventory as an asset: 'I have $50,000 in merchandise.' What they do not see is the cost of keeping that merchandise there. The cost of holding inventory includes storage space, insurance, deterioration, obsolescence, and above all, opportunity cost — that money could be earning returns elsewhere or buying products that actually sell fast.

In Latin America, the cost of holding inventory is especially high because of inflation. A product you buy today for $100 and sell in 3 months for $115 may look like a 15% gain. But if inflation during those 3 months was 12%, your real profit is minimal. In countries with high inflation, holding inventory without rotation is equivalent to slowly burning money. That is why control is not optional — it is survival.

ABC Analysis: Classify Before You Manage

ABC analysis is the first step to organizing your inventory intelligently. It is based on the Pareto principle: a small percentage of your products generates the majority of your revenue. The classification is simple but powerful.

Category A: the 20% of products that generate 80% of your revenue. These are your star products. They can never be out of stock. It is worth monitoring them daily and maintaining a high safety stock.
Category B: the 30% of products that generate 15% of your revenue. They are important but not critical. Weekly review and moderate stock is enough.
Category C: the 50% of products that generate only 5% of your revenue. They take up the most space and sell the least. Monthly review, minimal stock, and consider eliminating items that have not moved in 90 days.

What surprises many owners when they do this exercise is discovering that half their inventory generates barely 5% of their sales. They are dedicating space, capital, and attention to products that contribute practically nothing to the business. Freeing that capital and space for A-category products can transform profitability without needing to sell more — just selling smarter.

How to Do Your ABC Classification

ABC product classification by revenue

Example: 80/15/5 — 20% of products generate 80% of revenue

Export your sales history by product for the last 3 to 6 months.
Calculate the total revenue generated by each product.
Sort from highest to lowest revenue.
Calculate the cumulative percentage of total revenue.
Products adding up to 80% of revenue are A. From 80% to 95% are B. The rest are C.

Stock Levels and Reorder Point

The reorder point is the minimum stock quantity you should have before placing a new order. It is calculated based on two factors: how much of that product you sell per day (or week) and how long it takes for a new order to arrive once you place it (lead time).

The basic formula is: Reorder Point = Average daily consumption multiplied by Lead time in days, plus Safety stock. For example, if you sell 5 units daily, your supplier takes 7 days to deliver, and you want 3 days of safety stock, your reorder point is: 5 x 7 + (5 x 3) = 50 units. When you reach 50, it is time to order.

Safety Stock: The Buffer That Saves You

Safety stock is extra inventory you keep to cover demand variations or supplier delays. It is not waste — it is insurance against lost sales. For A-category products, safety stock should be generous (1-2 weeks of sales). For C-category products, it can be minimal or zero. In regions where suppliers sometimes run late, safety stock is especially important.

Stock levels over time

Example: product stock with reorder point marked

FIFO: First In, First Out

FIFO (First In, First Out) is an inventory rotation method where products that entered the warehouse first are the first to be sold. It is especially critical for perishable products (food, medicine, cosmetics), but it is good practice for any inventory because it prevents obsolescence and deterioration.

Organize your warehouse so the oldest stock is in front and the newest in back.
Label each batch with the date received to make rotation easier.
Train your staff to always pick from the front, never from the back.
Review monthly for products that have not moved in over 90 days — those need action (promotion, return, or write-off).
For products with expiration dates, FIFO is not optional: it is a legal and health obligation.

Murett manages your inventory automatically with FIFO lot tracking, low-stock alerts, expiration alerts, and reorder point calculations based on your actual sales data. Every sale decreases stock, every purchase increases it, and the system alerts you before you run out of what you need.

The 5 Most Common Inventory Mistakes

Overbuying for volume discounts: the supplier discount looks attractive, but if the product takes 6 months to sell, the holding cost outweighs the savings. Calculate before you decide.
Not doing periodic physical counts: the gap between theoretical inventory (what the system says) and actual inventory (what is on the shelf) grows over time. A partial monthly count and a full quarterly count maintain accuracy.
Treating all products equally: spending the same control effort on a product that sells $10,000/month and one that sells $50 is inefficient. Use ABC classification to prioritize.
Not measuring turnover: inventory turnover tells you how many times your stock renews in a period. A turnover of 12 (renews monthly) is excellent. A turnover of 2 (renews every 6 months) means stagnant capital.
Ignoring dead stock: products that have not sold in over 90 days are taking up space and capital. Run a clearance, return them to the supplier, or donate them — but do not leave them there hoping for a miracle.

The best inventory is not the biggest. It is the one that sells fastest with the least capital invested.

Inventory control is not glamorous, but it is one of the most direct levers for improving an SMB's profitability. Every dollar freed from dead stock is a dollar available to buy what actually sells, pay off debts, or invest in growth. And with the right tools, maintaining that control does not have to be a full-time job — it just requires the right data and the discipline to review it.