Inventory Management for Resellers: What to Track and How

Short answer

What is inventory management for a reseller?

Inventory management is knowing, for every item you own, what it cost, where it is, where it is listed and what it sold for. For a reseller that means one record per item from purchase to payout, so you always know your stock value, your profit after fees and which items are not selling.

1. Keep one record per item

Everything starts with a record for each item the day you buy it. Write down:

What it is: name, size, condition, and a SKU or style code if it has one.
What it cost: the price you paid plus buying fees and inbound postage.
When and where you bought it, for your accounts and returns.
Where it is: shelf, box or storage unit.
Where it is listed, and at what price, on each platform.
Once sold: the sale price, the platform, its fees, the postage and the date.

2. Watch a few numbers

Stock value at cost: what all your unsold items cost you. This is the cash sitting on the shelf.
Profit per sale after fees: the sale price minus cost, platform fees, payment fees and postage.
Markup and margin: profit compared with cost (markup) or with the price (margin). The markup calculator does both.
Inventory turnover: cost of goods sold ÷ average stock. It tells you how many times your stock sells through in a period.
Days in stock: how long each item has waited. Old items are where cash gets stuck.

3. A simple routine

Every purchase: create the record before the item goes on the shelf.
Every sale: mark the item sold, with the platform and fees, and end the other listings straight away so it cannot sell twice.
Every week: look at items that have sat longest and decide to reprice, bundle or move them to another platform.
Every month: count your stock against your records and check your stock value and turnover.

4. Spreadsheet or inventory app?

A spreadsheet is free and flexible, and fine for a few dozen items sold in one place. It starts to cost you time when items are listed on several platforms, when every sale needs its fees worked out, or when you want your stock value and profit without fixing formulas.

An inventory app keeps the same records but does the sums for you: profit after fees on each sale, stock value, turnover and aging stock. Retailed is free for up to 25 active items, so you can try it on part of your stock and keep your spreadsheet for the rest.

Updated 5 November 2026

Frequently asked questions

General4 questions

What should I track for each item?

At minimum: the item and its size or condition, the purchase price with any buying fees, the purchase date, where it is stored, where it is listed and at what price, and, once sold, the sale price, the platform, its fees and the postage. With those, every other number can be worked out.

Can I manage my stock in a spreadsheet?

Yes, many resellers start that way. A spreadsheet works while you have a few dozen items and one place to sell. It gets hard when you list the same item on several platforms, need fees worked out per sale, or want stock value and profit without rebuilding formulas.

How often should I count my stock?

Check what you think you have against what is on the shelf at least once a month, and every time you prepare a tax return or an accounts close. Small regular checks catch lost, damaged or double-sold items early.

Is there a free inventory app for resellers?

Retailed has a free plan for up to 25 active items, with inventory, sales, expenses and customers. Paid plans start at $19 a month and add CSV import, exports and more items.

Inventory management for resellers