Ryder here, from the Social Care Team at Shopify. Welcome to the Community and thanks for posting! I'd be happy to elaborate on the different ways you'd be able to calculate your cost of goods sold, and thus understand how much profit you're making.
Which plan are you currently on? The Shopify plan ($79/month USD) includes a wider range of reports than the Basic plan ($29/month USD) has to offer. Included in these additional reports are the Profit reports. Regardless of the plan you're on, you'll be able to add the cost per item within your product pages. This information won't be displayed publicly on your storefront; however, you won't be able to access the Profit Reports unless you're on the Shopify plan or higher. You can find the different types of reports available in each plan here.
If you're on the Basic plan or lower, you still have a couple of options. One way would be to create a Google Sheets, using the formula mentioned in our How to Calculate COGS guide. I highly suggest reading through its entirety; however, I've also shared the formula below:
[ Beginning inventory + Cost of purchases + Cost of labor + Cost of materials + Other costs ] - [ Ending inventory ]
Of course, keeping up with this information will require manual labor. Alternatively, you can consider using an app such as SimplyCost or Profiteer, or browse through some other options in our App Store. I hope one of these solutions helps you with your calculating needs! Please let me know if there's anything I can clarify.