Selnook

Selnook provides five free browser-based calculators for online sellers: profit margin, Amazon FBA, Etsy fees, eBay fees and landed costs.

Sellers can enter their own product, shipping, marketplace, payment and advertising costs to estimate per-order profit and compare break-even or target-margin prices. This helps with checking unit economics before choosing a selling price. Dedicated marketplace calculators make the assumptions visible and editable instead of promising a guaranteed business result.

The core calculators work without creating an account. Results are estimates based on entered values; sellers should verify current fee schedules and any omitted costs before making decisions. Selnook is maintained by an independent developer.