Free tools
Free tools for Amazon FBA sellers
PrepVia publishes two free calculators and a Chrome extension. The dimensional weight calculator shows which weight Amazon bills for a box. The placement fee calculator compares Amazon's 2026 inbound placement options. The PrepVia Sourcing Assistant shows Amazon fees, profit and selling restrictions on Amazon.com product pages, for PrepVia customers.
Which tool answers which question
| Your question | Tool | You enter | You get |
|---|---|---|---|
| Which weight will Amazon bill for this box? | Tool: Dimensional weight calculator | You enter: Box length, width and height, and the unit weight | You get: Dimensional weight next to the unit weight, and the greater of the two |
| Pay the placement fee, or split the shipment? | Tool: Placement fee calculator | You enter: Packaged dimensions, weight and units | You get: Size tier and Amazon's 2026 fee range for minimal, partial and optimized splits |
| Can my account sell this product, and what would I keep? | Tool: PrepVia Sourcing Assistant | You enter: Nothing to type: it reads the Amazon.com page you open | You get: Amazon fees, payout, profit and ROI at your cost, selling restrictions, Buy Box and sales rank |
All tools
- Dimensional weight calculatorLength times width times height divided by 139, next to the unit weight: see which of the two Amazon bills.
- Placement fee calculatorCompare minimal, partial and optimized split costs for an FBA shipment with Amazon's 2026 rates.
- PrepVia Sourcing AssistantChrome extension for PrepVia customers: Amazon fees, profit, ROI and whether your account can sell the item, on Amazon.com product pages.
- The PrepVia appWhere PrepVia customers send inventory, follow each shipment from check-in to Amazon and see expected versus received units.
Every number in these tools is Amazon's published rule or comes from your own seller account. The tool pages link to the Amazon page they follow. Pages reviewed on October 26, 2026.
Questions about the free tools
Are the PrepVia tools free?
Yes. The dimensional weight and placement fee calculators on prepvia.com are free and need no account. The PrepVia Sourcing Assistant is a Chrome extension for PrepVia customers: it reads Amazon data through the customer's own connected seller account.
Do the calculators use my Amazon account?
No. The calculators work with the numbers you type into the page. Only the Sourcing Assistant reads Amazon data, and it does so through your own seller account connected to PrepVia.
Where do the formulas come from?
From Amazon's published rules. The dimensional weight divisor of 139 and the 2026 placement fee tables are Amazon's numbers, and each tool page links to the Amazon page it follows.