How can I find out the profit margin on each item I sell?

Use the Profit By Item report (Sales category). It shows the gross profit per item — the difference between the selling price and the cost of goods sold — and lets you compare margins across your catalogue.

For cost-layer detail, use the FIFO Cost Lot Tracking report (Inventory Valuation category) to see which purchase lots are being consumed when each item is sold.

Learn more about Sales Reports and Inventory Valuation Reports.