Seller Profit Calculator app icon Seller Profit Calculator
iPhone App · One-time purchase

Every pricing decision.
Answered in seconds.

Four specialist calculators in one app. Check your profit. Build a price that hits your target margin. Find your maximum cost price. Model a buyer's discount offer. All with platform fees, delivery and sales tax built in — and your products saved so you never start from scratch.

Download on the App Store

Exclusive to iPhone  ·  One-time purchase  ·  No subscription

Why basic calculators fall short

Online selling involves four different questions. Most calculators answer one.

Profitable online retailing demands accurate numbers. A product that looks like 40% gross margin can deliver 18% net once platform fees, postage and VAT are included. That is not a rounding error — that is the difference between a viable product line and one that is quietly losing money.

A basic margin calculator does one thing: give it a cost and a price and it tells you a percentage. That is useful once. It does not tell you what to charge to hit a target margin. It cannot figure out the most you should pay for a product. It has no answer for a buyer asking for a discount.

And even for the calculation it does handle, it ignores the costs that define what you actually keep: platform fees, payment processing, delivery, sales tax.

Seller Profit Calculator is built around the four questions that independent sellers actually face — with every real cost factored in and your saved product library at the centre so the answer is always seconds away.

Basic calculator

Sale price£45.00
Product cost−£18.00
Platform feesignored
Deliveryignored
Sales taxignored
Apparent profit£27.00

Seller Profit Calculator

Sale price£45.00
Product cost−£18.00
Platform fees−£5.39
Delivery−£3.50
Sales tax−£1.80
Real net profit£16.31
Four modes, one app

The right calculator for every decision

Every pricing decision in online retailing maps to one of four questions. Seller Profit Calculator has a dedicated mode for each — switching between them without losing your product details.

Profit Check

"I know my price and my costs — what will I actually keep?"

Enter your sale price, product cost, delivery and platform fee structure. The app calculates gross profit, cash profit, gross margin percentage and markup — with the exact cash amount you are paying in platform fees shown in the breakdown, not just a rate.

Use when Reviewing whether a product line is still worth running, checking a completed sale, or comparing what you actually kept against what you expected.
Price Builder

"I need a 35% margin — what do I have to charge?"

Enter your costs and target gross margin percentage. The app works out the sell price you need to charge — accounting for the fact that platform fees are calculated as a percentage of the sale price, not your cost.

Why this matters: As the price changes, the fee changes, which changes the price needed to hit the margin. This is an iterative problem that cannot be solved with a simple formula. Price Builder solves it automatically and shows you the recommended sell price with the cash fee at that price.
Use when Building a new listing, moving a product to a new platform, or deciding whether a target margin is achievable at a price the market will accept.
Max Cost

"There's a product at this price — what's the most I can pay for it?"

Enter your intended sell price and target gross margin. The app calculates the maximum product cost that still delivers that margin after all fees, delivery and tax are deducted. If the supplier's price is above that number, the product does not work at your target.

Use when Sourcing at a trade show, market or supplier catalogue, evaluating a wholesale quote, or deciding whether to buy a job lot.
Discount Modeller

"A buyer wants 20% off — what can I actually offer?"

A buyer messages you asking for a discount. You need an answer quickly, and it needs to be right. Select the product from your library, then model discount percentages to see the new offer price, revised cash profit and the impact on margin — with platform fees and delivery recalculated at the new price.

Use when Responding to buyer offers on eBay, Etsy or Depop, running a sale, or deciding how much flexibility you have on a slow-moving line.
Every cost included

Real numbers, not approximations

Every one of the four calculators works from the same complete cost model. Profitable online retailing is not approximate — these are the inputs that turn a rough margin into a number you can build a business decision on.

Platform fees

Configure percentage fees and fixed charges for any selling platform. The cash amount you pay in fees is shown at the actual sell price — not an estimate.

Delivery

Include your postage and packaging cost as a fixed amount. Delivery is modelled as a real cost against profit, not treated as cost-neutral.

Sales tax

Apply a sales tax percentage where applicable. Shown as a separate line in the breakdown so the impact is always visible and explicit.

Product cost

Your base cost of goods — the starting point for all four calculations. Save it once in your product library and it is available instantly across every mode.

Configure your own fee assumptions for any platform. Seller Profit Calculator is not affiliated with any marketplace.

eBay Amazon Etsy Shopify Depop Vinted Facebook Marketplace Your own channel

Seller Profit Calculator is not affiliated with, endorsed by or sponsored by eBay, Amazon, Etsy, Shopify or any other marketplace. Platform names are used only to describe configurable fee modelling.

Your product library

Save once. Run any calculation, any time.

Every product you sell has a cost, a delivery charge and a typical fee structure. Entering that from scratch every time is friction you do not need.

  • Save a product once. Cost, delivery and fee structures are stored in the library and available to all four calculators instantly.

  • Faster decisions in the moment. When a buyer is waiting or a supplier is standing in front of you, the information is already there. Load the product in a tap and run the calculation you need.

  • Remodel when costs change. When platform fees shift or delivery charges increase, update the library once and remodel from there. Every calculator reflects the change immediately.

  • A pricing foundation for your range. Your library becomes a working record of the products you sell — costs, typical margins, fee structures — not a stock tracker, but the pricing data that sits underneath everything.

Real decisions, real situations

Built for the moments that matter

Every feature in Seller Profit Calculator exists to support a real decision. Here is how the four modes work in practice.

At a trade show or car boot Max Cost

A supplier shows you a product at £22. You sell on eBay with a 12.5% fee, standard postage at £3.50 and you need at least 35% gross margin. Is £22 too much to pay?

Max Cost tells you in seconds. If your maximum cost comes back at £19.40, you know the product does not work at your margin target — and you have a number to negotiate from.

Know your maximum before you commit — not after you have already bought the stock.

Building a new listing Price Builder

You have a product costing £14.00, delivery at £3.20 and you are listing on Amazon with a 15% referral fee. You want 40% gross margin. What should you charge?

Price Builder calculates the exact sell price — accounting for the fact that Amazon's 15% applies to whatever you charge. You see the recommended price, the fee in cash and confirmation the margin is achieved.

Set your price with confidence. No guessing, no spreadsheet, no iterative trial and error.

A buyer makes an offer Discount Modeller

A buyer on Etsy messages asking if you would take £28 on a £34 item. That is an 18% discount. You need to know immediately whether it works.

Load the product from your library. Model 10%, 15% and 18% discounts. You can see exactly what you keep at each level and respond with a confident counter-offer or acceptance — rather than guessing.

Answer in seconds with a number you have calculated, not one you have hoped for.

Reviewing a product line Profit Check

A product that looked profitable at launch has had its eBay fees restructured and your postage costs have risen. Run it through Profit Check with the current numbers.

If the margin has dropped below your threshold, you have the data to reprice, relist on a cheaper platform or discontinue. If it still works, you know that too.

Profitable online retailing requires regular reviews. The numbers should tell you — not your instinct.

See it in action

All four calculators. Two minutes.

Profitable online retailing demands that every pricing decision is made on accurate numbers — not estimates, not rough margins, not gut feel. Seller Profit Calculator gives you four specialist tools to make those decisions confidently, in seconds.

Download on the App Store
What's next

Part of a growing toolkit for independent online retailers

Seller Profit Calculator is the first part of a broader vision: practical, iPhone-first tools for people who sell products online. Future tools will connect pricing, inventory and seller workflow into a more complete suite for independent retailers — without the bloat of heavyweight ecommerce software.

Designed for people who want professional-grade clarity without enterprise-grade complexity.

Seller Profit Calculator Available now
Inventory Coming soon
More tools In development
One-time purchase

Four calculators.
One decision to make.

Profitable online retailing demands accurate numbers — not estimates, not rough margins, not gut feel. Seller Profit Calculator gives you four specialist tools to make every pricing decision confidently, from any situation, in seconds.

Available as a one-time App Store purchase. No subscription. No account required.

Download on the App Store

Exclusive to iPhone · Available now on the Apple App Store

FAQ

Questions about Seller Profit Calculator