What's it Costing You to Sell What You Sell?
Advertising, marketing, labour, storage and the catch-all category of overhead.
It's useful to know how much it costs you to get a product sold as well as what it costs you to create it.
What's Your Gross Profit Margin?
This is calculated by dividing your total sales into your gross profit. If your gross profit margin is staying consistent or trending upward, you're probably on track.
Being able to track a declining margin can give you a heads-up that you must adjust your prices or your costs. In the worst cases your gross profit and profit margin disappear altogether. At that point, you'll be like the fellow who lost money on every sale but figured he could make it up in volume. Don't do it.