E-Commerce Utility Calculators
A free calculator for the commercial arithmetic that determines whether an e-commerce order can make money: contribution margin, break-even ROAS, refund and discount drag, monthly targets, and shipping-threshold economics.
The problem
E-commerce sellers spend a lot of time doing margin calculations on the back of envelopes, in spreadsheet cells, or in their heads. The numbers involved are not complicated — but there are enough variables, platform-specific fee structures, and tax rules involved that getting to the right answer quickly is genuinely harder than it should be.
Sellers frequently assess ads, discounts, refunds and free shipping separately. That hides whether the combined order economics still leave a useful contribution after acquisition.
This is a narrow decision tool, not an accounting or marketplace-fee platform. It makes the assumptions visible and returns an answer immediately.
What it does
- Calculate contribution before and after advertising from sale price, product cost, fulfilment, fees, refunds, discounts, and ad spend
- Show break-even ROAS and warn when the current order economics cannot support paid acquisition
- Estimate monthly orders, profit, profit gap, and the conversion rate needed to reach a stated target
- Compare a free-shipping threshold with current contribution using a scaled product-cost assumption, not a one-unit shortcut
- Display-currency selector for modelling all inputs in one chosen currency; it does not perform FX conversion
- Mobile-first layout designed for quick in-context use — when you need the number, you need it now
- No login, no account, no data stored — open and use instantly
Product choices
The decisions that shaped this as a decision tool rather than a generic number cruncher.
One coherent model
The live calculator combines the inputs that determine whether an order and its acquisition cost can make money. It does not pretend to model marketplace-specific fees that the user has not entered.
Decision-first output
The output is framed as an answer to a decision, not just a number. Break-even ROAS shows the floor paid acquisition must beat; the profit gap shows whether conversion or order economics need attention.
No friction — no account required
Most financial tools want an email address before they show you anything. This does not. Open it, enter numbers, get an answer. The absence of onboarding is a deliberate product choice.
Assumptions made visible
The shipping-threshold result displays the estimated basket product cost and the cost-to-price ratio used. Users can change the representative product inputs when their basket mix is different.
Scope boundaries — and why
The things that were deliberately left out, and the reasoning behind each decision.
What worked
- The calculator puts product cost, fees, refund drag, discounts, fulfilment and advertising into one visible contribution model
- Break-even ROAS and target conversion translate arithmetic into practical acquisition decisions
- Shipping-threshold product cost scales with the basket rather than remaining fixed at one representative unit
- No-login design removes the biggest drop-off point for utility tools
Natural next steps
- Validate demand before building marketplace-specific fee calculators or an Amazon FBA module
- Scenario comparison — save two versions of the same calculation and compare them side by side
- Printable or shareable output for quoting landed costs to clients or suppliers
- Provider-backed fee lookup only when a maintained source and clear user demand justify it
Try the calculators
No login required. Enter your numbers and see contribution, break-even ROAS, monthly target economics, and the assumptions behind a free-shipping threshold.
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