Four tools for the questions that come up while sourcing: what Amazon will charge you, whether a product is worth buying at your cost, whether it will actually sell, and what a Keepa timestamp means. No account, no extension, no email.
Estimate Amazon referral fees, FBA fulfillment fees, and net profit from price, weight, and dimensions.
Open toolCalculate ROI, profit margin, and the maximum buy cost to hit your target return before you source.
Open toolConvert an Amazon Best Sellers Rank into an estimated monthly sales volume by category.
Open toolConvert Keepa minute-epoch timestamps into readable dates (and back) when working with raw Keepa CSV exports.
Open toolThey overlap less than the names suggest. Fees and ROI are different questions: the first is what Amazon takes, the second is whether what is left justifies the buy.
| The question | Tool | What you need to hand |
|---|---|---|
| What will Amazon charge me for this? | FBA fee calculator | Sale price, weight, dimensions, category |
| Is it worth buying at this cost? | FBA ROI calculator | Sale price, your unit cost, a target ROI |
| Will it actually sell? | BSR to sales calculator | A Best Sellers Rank and its category |
| What date is this Keepa number? | Keepa time converter | The minute value from a Keepa export |
All four run in your browser and none of them ask for anything first. That is worth stating plainly, because it is not the norm. Amazon's own FBA revenue calculator needs a Seller Central login, and several of the free calculators that rank for these searches want a signup or a Chrome extension before they will show you a number.
Nothing here is a trial or a teaser for a gated version. If you only ever use the calculators and never make an account, they will keep working. The paid product solves a different problem — the same math across a few thousand rows instead of one — and there is no version of that problem you have while checking a single ASIN.
If you want the reasoning behind the numbers rather than the numbers themselves, the sourcing guides cover Keepa data and FBA fees in more depth, and the glossary defines the terms these tools assume you already know.
These calculators give you fast, single-product answers. But real wholesale and arbitrage sourcing means evaluating hundreds or thousands of products from a supplier list. Gridwinner parses your CSV locally in the browser and runs the same fee, ROI, and velocity math across every row in one pass. Explore the full feature set to see how it works.
Gridwinner analyzes your entire supplier list in seconds: FBA fees, ROI, and winners, all at once.
Analyze your whole supplier list