Built for: Founders of supplement and wellness brands selling $3M or more a year on Shopify and Amazon.
What it answers: What each order really leaves you on each channel, where your cash is sitting, when to reorder and how to pay for it, and whether customers come back.
See it live: Supplement channel demo · a made-up company with invented numbers
"Amazon is half my sales. Is it half my profit?" It's the question I hear most from founders whose brand has outgrown its own Shopify store. Seller Central and Shopify will each tell you sales and a rough margin. Neither tells you what's left after every fee and ad dollar, or why the bank balance keeps going down while sales go up.
Here's how I'd walk a founder through it, using a sample dashboard we built for a made-up brand called Larchly. It sells twelve supplements on its own Shopify store (one-time orders and a monthly subscription at 15% off) and on Amazon through FBA. Three products, Magnesium Night, Daily Greens and Ashwagandha Calm, are about 70% of sales. A contract manufacturer makes everything on a ten-week lead time, with half paid up front.
Larchly sold about $6.1M in the last twelve months, up 39%. Amazon is 52% of that. But Amazon is only 40% of what's left after product, fees and ads.
The three waterfalls take each channel's last twelve months and scale them to a $40 order:
So one subscriber order is worth about two Amazon orders. Amazon still earns its place – it brings customers Larchly would never reach on its own – but it keeps the least per order, and it's the channel growing fastest.
Most founders quote gross margin – what's left after the product itself. Larchly's is about three quarters of net sales on every channel, so on that number Amazon and Shopify look the same.
The number that runs a product business is contribution margin – what's left after an order has been sold, shipped and marketed, before salaries and rent. That's where the channels split. Subscribers keep about 33% of net sales, because their next order needs no ad. New one-time Shopify orders keep about 18%: they have the best gross margin of the three, and then Meta and Google take about a third of the sale to find each buyer. Amazon keeps about 16% after the referral fee, FBA and Amazon ads.
Contribution margin is what pays for the team, the rent and the next run. That's why I'd grow the second order before the next Amazon ad.
This is the picture most founders have never seen. Larchly made about $225K in the last twelve months, and the bank is about $20K lower than a year ago. About $190K more is now sitting in stock at the 3PL and at Amazon, in deposits on the next runs, and in the payouts Amazon holds back. Another $70K went to the owners in January to pay their taxes on last year's profit.
That's what growing 40% costs when you pay for product ten weeks before it sells. It also means profit and cash need two separate conversations, and the cash one is what keeps founders up at night.
Last December's Magnesium Night run shipped 48 days late while the manufacturer waited on raw material. Magnesium Night was gone from Amazon from March 31 to April 19, and once it came back, Amazon sales took about two months to recover their ranking. That cost Larchly about $35K of what it would have kept.
Carrying three more weeks of Magnesium Night costs about $5K a year in storage and tied-up cash. That trade is easy once you see both numbers side by side, and it's where the reorder rule comes from: reorder when weeks of supply hit ten weeks of lead time plus three of safety.
The chart on the right is the next nine months, week by week, with every manufacturer deposit and balance marked. Daily Greens and Ashwagandha Calm are at or near their reorder point now. Pay for those runs, add the January insurance renewal and the owners' tax money, and the bank drops to about $30K in the week of February 7. The cards underneath show when each hero would run out at Amazon if no new run went in – Daily Greens first, at the end of January.
About 55% of new subscribers are still paying six months later. The ones who started this year hold noticeably better, because in January Larchly added skip-a-month and swap-a-product to the subscription portal. One-time buyers come back about 27% of the time within six months.
That's where the cheapest growth is. Every one-time buyer you turn into a subscriber at the second order is worth about two Amazon orders a month from then on, and you've already paid to find them.
The last section lines up the founder's moves by what they do to the cash low point:
The levers on the page let you try any mix. Half-size runs plus the line keeps Larchly above $150K all winter.
My advice to the founder: ask the manufacturer about half runs this month, before the January orders go in, and open the line while the P&L still looks good to a lender.
We connect read-only to Shopify, Seller Central, your bank and your accounting system, pull the settlement reports and POs that sit underneath them, and keep it all in a secure data warehouse that updates itself. Then a CFO who knows inventory brands reads it with you every month.
That's CFOptimize for Inventory Brands, and it starts with a free channel margin check on your own data: what each order keeps after every fee and ad dollar, where your cash is sitting, and when your next runs will pinch. Book your free channel margin check.
Mark
Larchly is a made-up company, and its manufacturer, 3PL, products and every number in the dashboard and this post are invented. Amazon's 15% referral fee for health and personal care items over $10 is its published rate for 2026; FBA and storage fees, price response, ad returns and the line of credit's terms are illustrative. Nothing here is investment, legal or tax advice.