If you sell on both eBay and Poshmark, use one inventory row per physical item and one sales row when it sells. A useful free spreadsheet connects those rows by SKU, then subtracts the actual cost of the item, marketplace fees, postage, packing materials, and other selling costs. It also rolls sales into a monthly profit and loss view. A file that only totals payouts will tell you how much cash arrived, but it cannot tell you which flips earned money.

The free Reseller P&L + Inventory Tracker is built for that workflow. It opens in Excel or imports into Google Sheets. It has an Inventory Log, Sales Log, Dashboard, and Monthly P&L, plus setup, fee-reference, and walkthrough tabs. The download is email-gated: enter an address to reveal the file and receive the weekly Reseller CFO email. The signup terms are shown beside the form.

The five columns that make the sheet useful

For each purchase, record the SKU, purchase date, source, cost, and physical bin before it disappears into storage. Add listing date, platform, and status when it goes live. For each sale, record sale date, SKU, item price, buyer-paid shipping, actual postage, and any packing cost. The SKU lets the sale pull the purchase cost you recorded earlier.

The tracker preprints stable INV-0001-style SKUs. They stay attached to the item when the sheet is sorted. If a sale points to an unknown SKU, the cost and margin cells show CHECK SKU; the workbook does not quietly treat missing cost as zero. Its Inventory Log also counts unsold items held for 180 days or more, so old stock becomes a number in units and purchase dollars.

The Monthly P&L groups sales and costs by month. It is a management view, not a tax return: estimated time and return reserves help with pricing decisions, while tax accounting requires its own records and review.

Check a template against a real sale

Suppose an item sells for $40 and the buyer pays $6 shipping. You paid $12 for it, $7 for the label, $1 for packing, and the platform charged $6.80 in fees. Your cash profit before shared overhead is:

$40 + $6 − $12 − $7 − $1 − $6.80 = $19.20

If a template reports $39.20 because it only subtracts the platform fee, it has skipped $20 of costs. If it reports the $46 order total as sales without subtracting postage, the shipping line is hiding the problem. The precise eBay fee also depends on category, Store plan, buyer sales tax, and optional services, so use the amount in your completed order when reconciling a sale; eBay publishes its current fee schedule.

When to use a spreadsheet

A spreadsheet is a good fit while you can enter each buy and sale reliably. It cannot automatically remove a crosslisted item after a sale, and the workbook's platform-fee formulas are estimates that need checking against completed orders. If double sales or manual entry are recurring problems, inventory software may earn its cost. Keep your SKU scheme and cost records portable either way.

Start with the free tracker and its sample walkthrough. Then set up a single SKU and bin system across eBay and Poshmark, and use the per-sale eBay profit formula when an order needs exact reconciliation.