About FBA Calcs

Who builds this

FBA Calcs was created by an Amazon FBA seller — someone who reads these fee statements every month, not a content team that scrapes them for traffic. I built the tools I kept wishing existed: a calculator that breaks out every fee bucket on one page, a break-even search that respects tier boundaries instead of rounding past them, and a reverse-pricing tool that works backward from the margin you actually want.

The short version: this is a working seller's spreadsheet, opened up as a website. Every rate in the tool is manually checked against Seller Central before it ships. Verified: October 2026

How the rates are kept honest

Amazon rewrites fee schedules a few times a year — fulfillment bands in January, fuel surcharges mid-year, peak storage surcharges in Q4. When that happens, I open the current Seller Central fee schedule, compare every band and category tier against what the tool holds, correct the mismatches, and only then publish. Nothing is auto-scraped; the comparison is done by hand, because a one-cent error in a rate card compounds across every unit you ship.

The audit trail is public on purpose:

• The fee change log lists every rate change with its effective date and what the tool did about it.
• The methodology page shows the exact formulas the calculator runs — referral tiers, dimensional weight, return amortization, the works.
• The current 2026 fee table shows the built-in US card side by side with the categories that override it.

Last rate re-verification: October 27, 2026, against the live Seller Central fee schedule.

Local-first by design

This site is static HTML and JavaScript. No login, no backend, every calculation runs locally in your browser, no data ever leaves your device. There is no account system, no Seller Central API connection, no price tracking, and no sales look-up behind any page — and there never will be, because that would be a business model aimed at you rather than a tool for you.

The only thing stored is your last set of inputs, kept in your own browser's localStorage so you don't retype a product's dimensions on your next visit. That copy stays on your machine. If you want to audit it yourself, open Devtools — there is nothing to hide and nothing to protect behind a paywall.

What you'll find here

Free tools (eight of them, all local)

• FBA Profit Calculator — net margin per unit with every fee bucket exposed.
• Reverse Pricing Calculator — work backward from a target margin.
• Referral Fee Calculator — category-tiered referral, including the threshold flips.
• Size Tier Optimizer — find the dimensional-weight savings in packaging.
• Return Loss Calculator — amortize returns by category rate.
• ACoS / TACoS Calculator — advertising efficiency against real contribution.
• Product Sourcing Scorecard — rank opportunities before you order inventory.
• Inventory Restock Calculator — reorder timing against lead time and cover.

Guides, FAQ and the rate card

• The 2026 FBA fee guide — the whole schedule explained in order.
• How to use the calculator and the rest of the FAQ section.
• The 2026 fee table — the numbers the tool ships with, audited.

Open the FBA Profit Calculator →

Disclosure

As an Amazon Associate I earn from qualifying purchases. FBA Calcs is not affiliated with Amazon. Estimates only — verify with your Amazon Seller Central fee preview.

No data ever leaves your device.