What is ROI (Return on Investment)?
Profit as a percentage of what you paid. The reseller’s measure of whether a buy was worth the money.
ROI is profit divided by what you put in, shown as a percentage. For a reseller, what you put in is the cost basis: the price you paid plus anything spent getting the item ready to sell.
Example: you pay £22 for a chore jacket and sell it on Vinted for £65. Vinted charges the seller no fee, so the profit is £43 and the ROI is 43 ÷ 22, about 195%. Margin on the same sale is 43 ÷ 65, about 66%. ROI tells you which buys to repeat; margin tells you what each sale keeps.