Inventory control methods for a small online shop, with examples

Published 8 October 2026 · 4 min read

Inventory control is deciding what to keep, how much of it, and when to buy more, so that cash is not stuck on the shelf and customers do not hear “sold out”. Textbooks list many methods; six of them are worth a small Facebook shop’s time. Here is each one in plain words, with an example in taka.

What inventory control is for

For a small shop its objectives come down to four: never run out of what sells, keep as little cash on the shelf as that allows, lose nothing to damage, expiry or theft, and know at any moment what you have.

Its functions are the jobs that get you there: recording every delivery and every sale, setting how much of each product to hold, deciding when to reorder and how much, checking the shelf against the record, and clearing what is not selling. The six methods below are the tools for those jobs.

1. ABC analysis: know which products matter

Sort your products by how much money each brought in over the last three months. The few at the top that make up most of your sales are your A products, the next group is B, and the long tail is C. If 8 of your 60 products brought in ৳3,00,000 of your ৳4,00,000 in sales, those 8 are your A list.

Watch A products every day and never let them run out, check B every week, and buy C only once it has sold.

2. Reorder point: when to buy more

Reorder point = what you sell in a day × the days your supplier takes to deliver. A size that sells 4 a day, from a supplier who takes 6 days, has a reorder point of 24: order more when 24 are left.

3. Safety stock: a cushion for a bad week

Sales jump and suppliers run late. Safety stock is the extra you keep for that. A simple version is your best day’s sales minus your usual day’s sales, times the supplier’s days. If that size usually sells 4 a day but sold 7 on its best day, safety stock is (7 − 4) × 6 = 18, and the reorder point becomes 24 + 18 = 42.

Keep safety stock for your A products. For C products, running out now and then costs less than the cash the extra would tie up.

4. First in, first out

Sell the oldest stock first by putting each new delivery behind the old one on the shelf. For cosmetics, food and anything else with an expiry date this is not optional; for clothes, it keeps last season’s colours from turning into stock nobody wants.

5. Economic order quantity: how much to buy at once

Every time you buy, it costs you: the trip to the wholesaler, the van, your day. Buying a lot at once ties up cash and shelf space instead. The economic order quantity balances the two: EOQ = √(2 × units sold a year × cost of one order ÷ cost of holding one unit for a year).

Say you sell 1,200 of a T-shirt a year, each buying trip costs ৳600 all told, and keeping one T-shirt for a year costs ৳20 in space, damage and the cash tied up. EOQ = √(2 × 1,200 × 600 ÷ 20) = √72,000, about 268. Buying around 270 at a time, four or five times a year, is the cheapest way to keep it in stock.

Treat the answer as a guide, not a rule: a supplier’s minimum order or the rush before Eid matters more than the formula.

6. Pre-orders and made to order

For products that are dear, bulky or uncertain to sell, take the order first and buy afterwards. Say clearly in the post that it is a pre-order and when it will arrive, and take an advance, so that a change of mind does not leave you holding the stock.

Perpetual or periodic: how you keep the count

A periodic system counts the shelf every week or month and works out what sold from the difference. A perpetual system takes every sale off the count as it happens, so the figure is right at any moment. A shop that sells in more than one place needs the perpetual kind, with a regular count on top to catch what the record missed.

Sells Pilot keeps a perpetual count for every size, so a sale on Messenger, Instagram, your shop website or the counter comes off at once. It records the buying price of each delivery, tells you when a size drops to its low-stock level, and its reorder page shows what is nearly gone and how fast it has been selling.