FBABase - Amazon FBA Profit Calculator

The formulas

Landed cost = supplier unit price + first-leg freight + prep & labeling

Referral fee = max(retail price × referral %, referral minimum)

Blended TACOS = ACOS × ad-attributed share of sales

Holding cost = storage + aged-inventory surcharge + cost of capital

Storage = unit volume × (off-peak months × off-peak rate + peak months × peak rate)

Cost of capital = landed cost × annual rate × days held ÷ 365

Operational cost = referral fee + FBA fulfillment fee + holding cost + advertising
+ return reserve + other Amazon fees

Net profit = retail price − landed cost − operational cost

Net margin = net profit ÷ retail price

ROI = net profit ÷ landed cost

Breakeven TACOS = profit before ad spend ÷ retail price

Breakeven ACOS = breakeven TACOS ÷ ad-attributed share of sales

How this FBA profit calculator works

Amazon takes its cut in several separate places, which is why a product that looks profitable on the supplier invoice can still lose money after it ships. This calculator pulls every per-unit cost into one view so you can see the real number before you commit to an order.

Nothing is estimated on your behalf. You enter your own costs and fee rates, and the page recalculates as you type. Every formula above is written out in full, and the methodology and accuracy page covers where the fee rates come from, how worked examples are checked, and what these tools do not verify.

It is also free in the way that needs no asterisk: no account, no API key, no trial, and no upload. The calculator is plain HTML and JavaScript, so every figure you enter - supplier prices, freight, margins - is computed on your own machine and stays there.

Why the standard formula overstates profit

Most advice reduces FBA profitability to selling price − COGS − referral fee. That formula has no sense of time in it, so it prices a unit that ships in a week exactly the same as one that sits for a year. In practice they are completely different products.

Three real costs scale with how long a unit sits on Amazon's shelf, and none of them appear in the basic calculation:

• Seasonal storage. Storage is billed monthly per cubic foot, and the Oct–Dec peak rate runs roughly three times the off-peak rate. A product that sells through in spring and one that carries stock across Q4 pay very different rent for the same shelf.
• The aged-inventory surcharge. Past roughly 180 days, Amazon adds an escalating monthly surcharge per cubic foot on top of normal storage, stepping up through age bands and jumping sharply past a year. This is the threshold effect where the fee structure changes character rather than just getting bigger.
• Cost of capital. Cash frozen in slow-moving stock earns nothing. Nobody invoices you for it, which is exactly why it gets left out - but a product turning twice a year ties up six times the working capital of one turning twelve times, at the same margin.

Switch the storage input to Time mode and enter how long the average unit sits. All three are priced from that one number, so two products with identical fees and identical prices stop looking identical the moment their inventory turnover differs. That is usually the real reason two sellers at the same revenue post completely different margins.

When stock has already gone slow, the liquidate or hold tool answers the follow-on question: given what the remaining units will cost you in storage, surcharge, and tied-up cash before they clear, is selling through still worth more than dumping them? What you originally paid is sunk and excluded from that comparison, because it is gone whichever way you decide.

What each input means

Retail price

What the customer pays, before tax.

Supplier unit price

What you pay the factory per unit, excluding shipping.

First-leg freight

Getting the goods from the supplier into an Amazon fulfillment center, divided across the units in the shipment. The shipment helper converts a freight invoice, duty, and other fees into this per-unit number.

Prep, labeling & packaging

Polybagging, FNSKU labels, bundling, and anything your prep center charges.

Referral fee

Amazon's commission, charged as a percentage of the retail price. Most categories sit at 15%, but it varies - see the full Amazon FBA fee tables for your category.

FBA fulfillment fee

The per-unit pick, pack, and ship charge, set by the product's size tier and weight. Don't know yours? The FBA fee calculator looks it up from Amazon's current rate card - it reports the 3.5% fuel surcharge as its own line, and the field above wants both added together.

Storage fee

Monthly warehouse storage, spread across the units you expect to sell. Enter a flat figure if you already know it, or switch to Time mode to price it from your unit volume and how long stock sits - including the Oct–Dec peak rate.

Days held before selling

How long the average unit waits in a fulfillment center before it sells. Your inventory turnover, in other words. Every holding cost below scales off it.

Months in Oct–Dec peak

How much of that shelf life falls inside Amazon's peak window, billed at the higher Q4 rate instead of the off-peak one.

Aged-inventory surcharge

The escalating monthly charge on stock stored past roughly 180 days, summed across the age bands the unit passes through rather than charged at the final band for its whole life.

Cost of capital

The annual return your cash would earn elsewhere - a loan rate, or what the same money would make in your next order. Applied to the landed cost for as long as the unit sits.

Advertising

Either your blended TACOS as a percentage of the retail price, or a flat ad spend per unit. This is charged to every unit, so it is not the ACOS Amazon reports - use the converter to turn one into the other.

Return & damage reserve

Money set aside for refunds, unsellable returns, and damage. Entering this as a percentage of price is usually closer to reality than a flat figure.

Frequently asked questions

How do you calculate FBA profit per unit?

Start with the retail price, subtract the landed cost of the unit (supplier price, first-leg freight, and prep), then subtract every Amazon-side cost: the referral fee, the FBA fulfillment fee, storage, advertising, and a reserve for returns. What is left is your per-unit net profit.

How do I calculate the true per-unit profit, not just the basic formula?

The usual shorthand - selling price minus COGS minus the referral fee - leaves out every cost that depends on time. Add the FBA fulfillment fee, advertising, a returns reserve, and then the three holding costs: monthly storage at the correct seasonal rate, the aged-inventory surcharge if stock sits past about 180 days, and the cost of the capital frozen in that inventory. Switch the storage input to Time mode, enter how long the average unit sits, and all three are priced from that. Products that look identical on the basic formula often diverge sharply once turnover is in the model.

How do seasonal FBA storage costs change the numbers?

Amazon bills monthly storage per cubic foot, and the October–December peak rate is roughly three times the January–September rate. Model it by entering how many of the months your stock sits fall inside that peak window - those months are charged at the peak rate and the rest at off-peak, rather than blended into an average that hides the spike. Carrying inventory through Q4 is the storage cost sellers most often forget, and on a slow-moving product it can be the difference between a workable margin and a loss.

What is the aged-inventory surcharge and when does it apply?

Once a unit has been in a fulfillment center for roughly 180 days, Amazon adds a monthly per-cubic-foot surcharge on top of normal storage, escalating through age bands and rising steeply past a year. This calculator sums the surcharge across every band a unit actually passes through, so stock that reaches 365 days is not billed the top rate for its entire life - that overstatement is a common spreadsheet error. The band your entered shelf life falls into is shown beneath the inputs so you can check it against current rates in Seller Central.

How do I factor in the capital cost of inventory?

Enter your cost of capital as an annual percentage - your borrowing rate, or the return the same cash would earn in your next inventory order. It is applied to the landed cost for as long as the unit sits, so a product turning twice a year carries roughly six times the capital cost of one turning twelve times at the same margin. Nobody sends an invoice for this, which is precisely why it is the cost most often missing from a profitability model.

Should I liquidate inventory at a loss, or keep holding it?

Compare the cash each path actually returns, and ignore what you paid for the stock - that money is spent either way, and letting it drive the decision is the sunk cost fallacy that keeps dead inventory on the shelf. The liquidate-or-hold tool works out how long your remaining units take to clear at your current sales rate, charges the storage, surcharge, and capital cost the average unit accrues while waiting, and sets that against what a liquidator or clearance price would net you today. If holding loses to dumping, the stock is costing you money to own.

What is a good profit margin for Amazon FBA?

Most established FBA sellers aim for a net margin somewhere between 15% and 30% after all fees and advertising. Below roughly 10% you have very little room for a fee increase, a price war, or a bad returns month. Margin alone does not tell the whole story, though, because it ignores how much cash you had to tie up to earn it. For the full picture - benchmarks, failure modes, and a pre-purchase checklist - see is Amazon FBA profitable in 2026?

Why is my ROI different from my profit margin?

They measure against different things. Margin divides profit by the retail price and answers "how much of each sale do I keep?" ROI divides profit by your landed cost and answers "how hard is my cash working?" A cheap product can post a modest margin and still show excellent ROI, which matters when your capital, not shelf space, is the constraint on growth. To go deeper - including annualizing ROI by your inventory turns - use the FBA ROI calculator.

What is breakeven ACOS and how is it calculated?

Start with breakeven TACOS: your profit before ad spend divided by the retail price. That is the most you can spend on advertising as a share of total revenue, and it is what the results panel above shows. Breakeven ACOS is that figure divided by your ad-attributed share of sales, because Amazon measures ACOS against ad-driven revenue only. The two are equal when every sale comes from an ad, and breakeven ACOS is higher whenever some sales arrive organically. Enter your ACOS and attributed share in the converter and it reports both. Spend under your breakeven and the sale is profitable; spend over it and you are buying revenue at a loss.

Does this calculator use current Amazon fee rates?

No, and that is deliberate. Referral percentages, fulfillment fees, and storage rates change over time and vary by category, size tier, and season. You enter your own figures, taken from Seller Central for your specific product, so the result reflects what Amazon actually charges you rather than a generic table that quietly goes stale. For a dated reference of the current rates, see our guide to Amazon FBA fees in 2026.

Does it handle returns and refunds?

Yes, through the return and damage reserve. Set it as a percentage of the retail price to model a typical return rate, or as a flat amount per unit. Categories like apparel carry far higher return rates than most, and ignoring that is one of the commonest ways a spreadsheet overstates profit.

Is my data saved or sent anywhere?

No. The calculator runs entirely in your browser, with no account and no API. Your supplier costs, prices, and profit figures are computed on your own device, and the records you save live in your browser's local storage - they never leave it. Clearing your browser data deletes them, and nobody else, including us, can read them. The page does load one external file, a cookieless Cloudflare script that counts page views and page speed; it cannot see anything you enter. The privacy policy sets out exactly what it collects.

Is this FBA calculator really 100% free?

Yes - free to use, with no registration, no paid tier, no trial clock, and no usage limit. There is nothing to sign up for because there are no accounts at all. The tool is a single static page: once it has loaded, it needs no API and no connection to keep working.