Price & Margin Calculator

A single-file tool that shows your real margin after fees. Enter cost per unit, selling price, and platform/payment fee percentage, and it shows profit per unit, margin on price, markup on cost, fee per unit, profit after fees, break-even units per month, and monthly profit at your planned units. No backend, no account, nothing is uploaded anywhere — everything runs on the buyer's own computer, offline, in any modern browser. If profit per unit is zero or negative, break-even honestly shows as impossible at that price.

What's inside: index.html (the whole tool: inputs, live results, how-to-read guide); README.md (how to use, fee-combining note, honest-limit notes).

License: Use this tool for your own business. Do not resell or redistribute the file.