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E-commerce & Online Selling

Marketplace fees, product margins, ad break-even and inventory math. 20 free tools, each one showing the math behind its answer and running entirely in your browser.

E-commerce pages answer the arithmetic of selling online: what a marketplace keeps in fees, what one unit really clears after the product cost and the shipping, where an ad campaign breaks even, and what holding inventory costs across a year.

Every page prints the formula it used, and each one states what it does not pretend to know. Nothing here forecasts how many you will sell - that is a market, not a formula - so the tools stop at price, cost, fees and cash flow, the numbers a seller can check against a statement.

Rates drawn from a platform’s published schedule are dated on the page, because seller fees change; whenever a number is the seller’s own estimate - a freight rate, a return rate, a conversion benchmark - the page labels it as one instead of dressing it up as fact.

All 20 E-commerce & Online Selling tools

Ad Break-Even CalculatorSee how many units an ad campaign has to sell before it earns back its spend: break-even units, sales and ROAS from your price, margin and ad budget.Find the sales an ad campaign must drive →
Amazon FBA Profit CalculatorWork out the clear profit per unit when selling with Amazon FBA: referral fee, fulfillment fee and product cost all subtracted from the sale price.Work out clear profit per unit on FBA →
Average Order Value CalculatorRevenue divided by orders is the average order value, and the reverse turns a target basket size into the order count it needs. Plan order volume from a number.Turn revenue into a per-order number →
Cart Abandonment Cost CalculatorThe revenue sitting in carts people abandoned, and how much a recovery flow can win back - a dollar figure to set against the send, not just a rate.Put a dollar figure on abandoned carts →
Conversion Rate CalculatorOrders divided by visitors is the conversion rate, and the reverse shows the traffic a target order count needs at the rate you expect. Plan visits from orders.Turn visits into an order rate →
Customer Acquisition Cost CalculatorWhat one new customer costs when acquisition spend is shared across the channels that earned them - blended and channel by channel, from the spend you entered.Price what a new customer costs →
Customer Lifetime Value CalculatorThe contribution a steady customer is worth over their whole relationship: average order value, frequency, lifetime and gross margin, from your numbers.Price what one customer is worth →
Dimensional Weight CalculatorWhat a carrier bills when a light but large box is priced by volume, not weight: the dimensional weight, the 1-cubic-foot threshold and the billable pounds.Find a box’s billable weight →
Discount Margin CalculatorSee what a discount leaves behind: the margin after the coupon, the profit on the sale price, and how many extra units a promotion must win to pay for itself.See what a discount leaves behind →
eBay Fee CalculatorWhat one eBay sale clears after insertion and final value fees: category rates from eBay’s own fee page, the per-order fee, and the proceeds you keep.See what a sale nets after eBay fees →
Etsy Fee CalculatorSee what a sale really clears on Etsy after the listing fee, the transaction percentage, payment processing and any off-site ad fee.See profit after Etsy fees on a sale →
Free Shipping Break-Even CalculatorSee how many extra orders free shipping has to win to pay for the delivery fee you stop collecting, from your order value, margin, shipping charge and volume.Know what free shipping costs you →
Inventory Holding Cost CalculatorTotal what your stock really costs each year: capital tied up, warehousing, insurance and shrinkage, added up from the rates you set.Cost what holding stock really costs a year →
Inventory Turnover CalculatorHow often your stock sells out in a year, and the days it takes to turn once - the ratio that shows whether money is moving through the shelf or sleeping on it.See how often your stock sells out →
Marketplace Fee ComparisonWhat one sale costs on Amazon, Walmart and eBay: each marketplace’s own referral-fee rate for the category, the fee it takes, and what that sale keeps on each.Compare what Amazon, Walmart and eBay take on one sale →
Product Pricing CalculatorPrice a product from its cost to hit the margin you want: the sale price that leaves a target margin after product cost and per-unit overhead.Price a product for your target margin →
Refund & Return Cost CalculatorWhat one returned order costs you to handle: the postage already spent, the return leg, the payment fee the processor keeps, and the inspection.Price what a returned order costs you →
Reorder Point CalculatorThe stock level that should trigger a new order: units sold during the lead time plus a buffer of safety stock. Reorder before the shelf runs empty.Find the stock level that restocks in time →
Shopify Cost of Selling CalculatorWhat a Shopify store really costs a month: the plan subscription plus card processing, from Shopify’s own pricing page, at your order volume.Price a month of Shopify plus payments →
Wholesale to Retail Margin CalculatorTurn a wholesale cost into a retail price and see the margin on the price, the markup on cost and the break-even retail price below which you lose money.Work out margin from wholesale to retail →

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