The problem we set out to solve
Amazon is the world's largest product marketplace. Yet the math behind a good decision — true margin after fees, viable ad spend, inventory payback, real unit price — is scattered across spreadsheets, paid SaaS tools, and Seller Central screens that require credentials you may not have yet.
On the seller side, a beginner sourcing their first private-label SKU often discovers FBA economics only after money is committed. On the buyer side, a "value pack" that looks cheaper on the listing page is frequently more expensive per ounce once pack size is normalized — but comparing units manually is tedious enough that most people do not bother.
Both sides share the same underlying failure: the decision happens before the math does. Herminox exists to flip that order.
Our north star
We want Herminox to be the first place a thoughtful person opens when an Amazon number matters — whether they are modeling a $4 margin on a kitchen gadget or comparing two protein powder sizes before checkout.
That means every tool on this site must pass four tests:
- Instant — open the page, type a number, get an answer. No account wall.
- Private — your inputs stay on your device. We are not building a data business on the side.
- Honest — we show the formula, cite the fee source, and state what we cannot know.
- Durable — static pages that load fast, work on mobile, and survive fee-schedule updates because we maintain them.
What we optimize for
Clarity over cleverness
A calculator that returns one number without context is dangerous. A 22% margin looks healthy until you subtract expected PPC and returns. Our seller tools are designed to be used in sequence — margin first, ad ceiling second, payback third — and our editorial content explains the thresholds experienced operators actually use.
Privacy as a product feature
We chose a client-side architecture because it is the right default for financial inputs. Your landed cost, your ad budget assumptions, and your purchase history are not our business. The Return & Capital Dashboard stores entries in your browser's local storage only; clearing your browser data clears the dashboard. No sync, no cloud, no "create an account to save."
Accessibility of expertise
Large sellers employ analysts. Small sellers and everyday buyers do not. Tiered referral fee math, holiday return extensions, and dimensional-weight edge cases should not require a $200/month tool or a week on Reddit. We publish the logic openly on each calculator page so you can verify it, learn from it, and apply it elsewhere.
Independence
Herminox is not affiliated with Amazon. We are not funded by course sellers, agency referrals, or display advertising. That independence lets us recommend conservative assumptions — include the fuel surcharge, model returns, stress-test slow inventory — without worrying about which upsell converts.
Who we build for
- First-time FBA sellers vetting a product idea before their first Alibaba message.
- Experienced operators who need a fast sanity check without logging into Seller Central.
- PPC managers setting campaign ceilings from actual margin, not industry averages.
- Budget-conscious households comparing unit prices across pack sizes on Amazon.
- Anyone who has ever missed a return window because the holiday policy added thirty invisible days.
What success looks like
We will know Herminox is working when:
- A seller passes on a SKU because margin after fees and expected ads falls below their floor — before placing a purchase order.
- A buyer chooses the smaller listing because per-unit math proves it is cheaper — not because the marketing copy said "best value."
- Someone shares a Herminox link in a forum with the words "runs in your browser, no signup" — because that combination still feels rare.
We measure reach through usage and search, not through accounts created. We do not need your email to know whether the tools are useful.
What we are building toward
The current six calculators cover the highest-leverage decisions we see repeated across seller and buyer communities: pre-list margin, ad ceiling, cash payback, unit comparison, lifetime cost, and return deadlines. We intend to expand the set carefully — each new tool must earn its place by answering a specific, high-stakes question that existing tools do not.
Every addition will follow the same principles: client-side execution, published methodology, mobile-ready layout, and zero paywall.
Our commitment to you
Herminox will remain free to use, free of third-party tracking scripts, and transparent about its limitations. We will update fee tables when Amazon publishes changes. We will not sell your calculator inputs because we never receive them.
If this mission resonates, use the tools, share them, and send corrections when Amazon moves faster than we do: hello@herminox.com.
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