Profit does not equal markup. Profit is simply that...profit, the amount you take away after all other costs and expenses.
So the answer is, it totally depends on your business. If you have a dollar (the product), and you have a store that you sell it in, with a sales staff, and electric bills, etc etc etc, you have to build a portion of those business costs into your markup. Let's say those overhead and administrative costs amount to a 40 cent markup. Your cost of the product is now $1.40.
Had you sold that dollar for $1.20...you actually lose 20 cents. If you sell it for $1.40, you break even and earn no profit. If your desire is to bring home 20% profit in that scenario, then you must charge $1.68. or $1.40 x 1.2
So again, how you calculate profit depends entirely on your business costs and how your business is structured.
You're welcome.