The break-even point is the level of sales where you make exactly zero profit. Everything below it loses money; everything above it earns. For ecommerce, calculating it correctly means loading in the fees and per-unit costs most sellers forget.
The break-even point is the level of sales, measured in units or in revenue, at which total revenue exactly equals total costs, so profit is zero. Below the break-even point the business loses money; above it, each additional sale contributes to profit.
It is one of the most practical numbers in ecommerce because it answers a concrete question: how much do I need to sell to stop losing money? Every pricing decision, every product launch, and every fixed-cost commitment changes where that line sits.
The break-even point only means anything if the costs feeding it are accurate. Build it on estimated COGS or forgotten marketplace fees and the line lands in the wrong place, which is why this metric is so closely tied to bookkeeping accuracy.
Break-even rests on two cost categories:
The bridge between them is contribution margin:
Contribution margin per unit = Selling price - Variable cost per unit
And the break-even point itself:
Break-even point (units) = Fixed costs / Contribution margin per unit
To express it in revenue rather than units:
Break-even point (revenue) = Fixed costs / Contribution margin ratio
where the contribution margin ratio is contribution margin per unit divided by selling price.
A seller has the following:
First, variable cost per unit = $15 + $9 = $24.
Contribution margin per unit = $40 - $24 = $16.
Contribution margin ratio = $16 / $40 = 40%.
Now:
So this seller must sell 750 units, or $30,000 in revenue, every month just to reach zero profit. Unit 751 is the first one that actually earns.
| INPUT | VALUE |
| Selling price | $40 |
| Variable cost per unit | $24 |
| Contribution margin per unit | $16 |
| Contribution margin ratio | 40% |
| Monthly fixed costs | $12,000 |
| Break-even (units) | 750 |
| Break-even (revenue) | $30,000 |
The textbook formula is simple. The ecommerce reality is that the variable cost per unit hides several costs sellers routinely leave out, and each omission pushes the break-even point lower than the truth.
Landed COGS, not factory cost. The $15 above must include freight, duties, and inbound shipping, not just the supplier invoice. Omit those and break-even looks easier than it is.
Marketplace fees vary by channel and product. Amazon's referral fee differs by category, FBA fulfillment depends on size and weight, and TikTok Shop, Walmart, and eBay each have their own structures. A blended fee assumption distorts break-even for any specific SKU.
Returns and reimbursements. A product with a high return rate carries hidden variable cost. Returned units may be unsellable, and you still paid to ship and fulfill them.
Ad spend. For acquisition-dependent products, advertising behaves like a variable cost. If you cannot sell a unit without paying to acquire the customer, that cost belongs in the break-even math.
Each of these understates variable cost when ignored, which overstates contribution margin, which makes break-even look closer than it is. A seller who thinks they break even at 750 units may actually need 950, and they will not know it until the month closes light.
Once you know the line, several decisions sharpen:
Notice that every input in the break-even formula comes from your books: landed COGS, marketplace fees by channel, and fixed costs. If those are estimated or blended, your break-even point is wrong, and wrong in the dangerous direction, because the omitted costs always make break-even look easier. We cover the broader downstream damage of bad cost data in the real cost of inaccurate COGS (/blog-posts/real-cost-of-bad-books-cogs).
ConnectBooks tracks real per-unit landed COGS with FIFO and splits marketplace fees by settlement and channel, which means the variable cost figure in your break-even calculation reflects what each unit actually costs rather than a guess. Accurate inputs put the break-even line where it really sits.
| NEXT STEPBreak-even is only as accurate as the costs behind it. See how ConnectBooks tracks real per-unit cost and per-channel fees at /pricing. |
It is the level of sales, in units or revenue, where total revenue exactly equals total costs and profit is zero. Below it the business loses money; above it each sale contributes profit. It tells a seller exactly how much they must sell to stop losing money.
Break-even units equal fixed costs divided by contribution margin per unit, where contribution margin per unit is the selling price minus variable cost per unit. To express it in revenue, divide fixed costs by the contribution margin ratio (contribution margin per unit divided by selling price).
Because they leave variable costs out. The variable cost per unit must include landed COGS (freight and duties, not just factory cost), marketplace referral and fulfillment fees, payment processing, returns, and often ad spend. Omitting any of these overstates contribution margin and makes break-even look closer than it really is.
Contribution margin is the profit a single unit contributes after its variable costs (selling price minus variable cost per unit). Break-even uses that figure to find how many units are needed to cover fixed costs. Contribution margin is per unit; break-even is the total volume those units must reach.
Raising price increases contribution margin per unit, which lowers the number of units needed to break even. For example, a seller with $16 contribution margin and $12,000 in fixed costs breaks even at 750 units; raising contribution margin to $20 by lifting price drops break-even to 600 units.
Clean, accurate books make this manageable. Start a free trial of ConnectBooks to get settlement-level accuracy and real margin visibility for your ecommerce business. No credit card required.
Running an e-commerce business comes with plenty of challenges, but ConnectBooks is here to make your life easier. With real-time insights, seamless integrations, and detailed tracking of your profitability and inventory, you can stay ahead of the game. Whether you’re selling on Amazon, Shopify, Walmart, TikTok or eBay, ConnectBooks helps you manage your finances with 100% accuracy and confidence, so you can focus on growing your business.
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