What a markup calculator is doing
Markup starts from cost and adds an increase on top of that cost to produce a selling price. If an item costs 80 and the markup is 50%, the markup amount is 40 and the selling price becomes 120. That is why a markup calculator is useful as a quick calculator and pricing calculator: it translates a cost base into a price without having to work the percentage out manually each time.
This kind of online calculator is especially useful for quoting, retail pricing, menu pricing, and service pricing where cost is known first and the desired uplift is chosen second. For users searching a free online calculator, cost calculator, or planning calculator, the most useful outputs are usually selling price, markup amount, resulting profit margin, and the price required for a target margin goal.