Markup has a very simple definition, it is the amount added onto costs to create a sales price. Notice something really important with that definition, it does not define profit. It merely defines how much to charge over costs so you can make a profit.
Margin is a term commonly used in calculating the percentage of profit on sales. Margin sometimes gets misused in calculating markup on costs.
It is amazing how one simple formula can be so confusing to the average business owner. The formula is markup. It is defined as the dollar amount or percentage of the cost of the item added to the item to equal its sales price. Many entrepreneurs especially those in retail confuse this simple formula with margin.