Open the calculator → See Understanding Landed Cost, Margin, and Markup for why these two numbers are so often confused.
What it solves for
Enter any two of cost, price, margin, or markup, and it solves for the other two — useful whether you're starting from a target margin and need to find the price, or starting from a competitor's price and want to know what margin or markup it implies against your cost.
Why margin and markup aren't interchangeable
Margin is profit as a percentage of selling price; markup is profit as a percentage of cost — the same dollar profit produces two different-looking percentages, and confusing which one a target refers to leads directly to mispriced products. See the worked example in Understanding Landed Cost, Margin, and Markup for the exact numbers.
A quick worked example
Cost = $6.00, target margin = 60%. Price = Cost ÷ (1 − margin) = $6.00 ÷ 0.40 = $15.00. The same $6.00 cost at a 60% markup instead would be Price = Cost × (1 + markup) = $6.00 × 1.60 = $9.60 — a very different price for a number that sounds similar.
Where to go next
This calculator solves the margin/markup math against your landed cost alone. Once you're ready to include marketplace fees, fulfillment, advertising, and returns, move to the Product Profitability Calculator for the fuller picture.