2 articles about Poshmark selling.

Poshmark Shipping Costs: Who Pays and How Profit Changes
The buyer pays Poshmark's flat shipping rate, until a discount or a heavy box moves the cost to you. Here is the math on what you keep.

How to Sell on Poshmark and Track Your Profit
Learn how to sell on Poshmark from first listing to payout, and see what fees, offers and shipping discounts do to the profit you keep.