Markup and margin are not the same number, and mixing them up quietly eats profit. Enter cost and price for both figures, or work backwards from a target.
Markup is profit as a percentage of cost; margin is profit as a percentage of the selling price. A $60 cost sold at $100 is a 66.7% markup but a 40% margin. To hit a target margin: price = cost ÷ (1 − margin). To hit a target markup: price = cost × (1 + markup).
Why is my 50% markup only a 33% margin? Different bases: markup divides by cost, margin divides by the (larger) price. It is the same dollars of profit either way.
Which one do retailers quote? Margin, usually called gross margin. Marketplaces and accountants work in margin; markup is common in trades and quoting.