Revenue isn't profit
A store can post $80,000 in monthly sales and still lose money. Product cost, shipping, payment fees, refunds, ad spend, app subscriptions and marketplace commissions all take a bite. By the time they're done, the margin can be a sliver.
The calculators on this page exist so you see that sliver before you commit to a product, a price or an ad budget. Each one works in your browser, with your numbers, and nothing gets saved on our side.
Marketplace and platform profit tools
The Amazon FBA calculator uses the fee tables from the 2026 Q2 excerpt. It handles the referral fee and its floor, the fulfillment fee ladder by size and weight, and shows per-unit KPIs. You can multiply the result across a time horizon to see what a full quarter looks like.
The Etsy calculator works out profit per order. Etsy charges a listing fee, a transaction fee on price plus shipping charged, and payment processing. If you use Offsite Ads, there's a toggle for that cost too.
The Shopify calculator compares Basic, Shopify and Advanced at your sales volume. It factors in plan fees, whether you use Shopify Payments or a third-party gateway, your apps, and the customer acquisition cost per order. The cheapest plan is not always the cheapest at scale.
The print-on-demand calculator compares Printful, Printify and Merch by Amazon, with a stacked cost breakdown and a break-even price.
Ad and growth math
Break-even ROAS is the number most new advertisers skip. It tells you the minimum return on ad spend you need just to cover variable costs. If your break-even ROAS is 2.4 and your campaigns deliver 2.0, scaling spend scales your losses.
The LTV to CAC calculator looks at lifetime value against acquisition cost. It handles both one-time purchase stores and subscription businesses, shows payback in months and gives a health band. A common rule of thumb is an LTV that's at least three times CAC, though it depends on your cash position.
The AOV optimizer models three levers: a free shipping threshold, an upsell and a bundle. It shows new average order value, the monthly revenue lift and the extra gross profit each tactic would bring.
- Break-even ROAS for ad campaigns
- LTV to CAC with payback months
- AOV optimizer for shipping thresholds, upsells and bundles
Pricing and inventory
Markup and margin get confused all the time. A 50 percent markup is a 33 percent margin. Mix them up and you underprice every item. The markup calculator shows both side by side, and the wholesale markup tool walks through cost, wholesale price and retail price, with keystone badges for the classic double-up.
The inventory turnover calculator gives you turnover, days on hand and holding cost. It also shows how much cash you'd free up by hitting a target turnover rate. For many small stores that cash is the difference between reordering on time and missing a season.
Mistakes that quietly kill margin
Forgetting returns is the big one. If ten percent of orders come back, you lose the sale, often the shipping both ways, and sometimes the product itself. Enter a realistic refund rate, not zero.
Pricing from competitors instead of costs is another. A rival might have cheaper supply, bigger volume or investors paying for losses. Your price has to work with your numbers.
Ignoring payment fees hurts at low prices. A flat 30 cent fee on a $9 item is over three percent before the percentage fee even starts.
And then there's free shipping. It converts well, but someone pays for it. Build it into the price or set a threshold that raises order value enough to cover it.
How to use these tools in order
Start with unit economics for one product. Use the platform calculator that matches where you sell. Get the per-unit profit.
Next, take break-even ROAS from that profit and compare it to what your ads actually return. If the gap is negative, fix price or cost before you touch ad budgets.
Then check LTV to CAC. A product with thin first-order profit can still work if customers reorder. A one-and-done product can't.
Last, look at inventory. Good margins don't help if cash sits on a shelf for six months.
About the fee numbers
Platforms change fees often. We update the defaults when we see changes, but always check your own seller dashboard before a big decision. Every field in these tools can be edited, so you can drop in your exact rates.
The results are estimates for planning. They aren't tax or accounting advice.
One order, every cost
Take a 40 dollar item that costs you 14 to buy. The marketplace charges 15 percent, which is 6. Payment processing takes about 1.50. Shipping you pay is 5, packaging is 0.80, and a 3 percent return rate costs you around 1.20 per order on average. That leaves roughly 11.50, not 26.
Now add advertising. If it takes 8 dollars of ad spend to get one sale, you're at 3.50 profit, a margin under 9 percent. A small change in ad cost or shipping can wipe it out. This is why a spreadsheet that only subtracts product cost from price lies to you.
Run your real numbers through the profit tools before you scale anything.
Break-even and the ad budget
Break-even ROAS tells you how many dollars of revenue each ad dollar must bring back before you start losing money. If your margin after costs, before ads, is 35 percent, you need a ROAS above about 2.9 just to break even. Anything under that, and every sale loses a little.
Most sellers aim well above break-even, since they also want to pay themselves. Set a target ROAS, check it weekly and cut campaigns that sit below the line for more than a couple of weeks.
Don't judge a single day. Ad data is noisy, and a bad Tuesday proves nothing.
Stock, cash and the traps
Inventory ties up money. A product that sells a unit a week but sits in a box of 200 ties up your cash for years. Order sizes should follow sales speed, supplier minimums and storage costs, not just a good unit price.
Watch out for slow stock that attracts storage fees. Some platforms charge extra for items that sit too long, and the fee can eat more than the profit.
Keep a small buffer, but resist the urge to buy in bulk for a tiny discount.
Keep the estimate honest
Fee schedules change often, and they vary by category and country. Treat the results here as planning figures and check your platform's current rate card before you commit. Your numbers stay in your browser.