What break-even actually asks
Break-even analysis answers one question: how much do I have to sell before the money coming in matches the money going out? Not before I am rich, not before the business is good — before it stops losing. It is the floor of the whole plan, and everything above it is measured from there.
The reason the question has a clean answer is that costs split into two kinds that behave completely differently. Fixed costs happen whether you sell nothing or sell everything: the lease, the salaries, the accountant, the software subscriptions, the insurance. Variable costs exist only because a sale happened: the materials, the packaging, the shipping label, the payment fee. Sell one more unit and the fixed side does not move while the variable side goes up by exactly one unit's worth.
That asymmetry is what makes a break-even point exist. Revenue grows with volume in a straight line from zero. Total cost grows with volume too, but starts high — at the fixed cost — and climbs more slowly, as long as each unit brings in more than it costs. Two straight lines with different slopes cross exactly once, and that crossing is the break-even point.
Contribution margin is the number that moves
The gap between the price and the variable cost of one unit is the contribution margin, and it is the axis the whole subject turns on. Sell a $50 item that costs you $20 to make and deliver, and each sale contributes $30 towards the fixed cost. Until the fixed cost is paid off, that $30 is not profit. Once it is paid off, every further $30 is profit in full.
So the break-even point is simply fixed cost divided by contribution margin. $12,000 of fixed cost at a $30 margin needs 400 units. Multiply by the price and you get the break-even revenue: $20,000. The two answers are the same fact stated in different units, which is why the revenue figure in this calculator is always exactly the unit figure times the price.
Thinking in contribution margin rather than in profit is what changes the decisions you make. Profit is an outcome you observe at the end of the month; contribution margin is a lever you can pull today. Raise the price by $5 and the margin goes from $30 to $35, and the break-even falls from 400 units to 343 — a 14% cut in the volume you need, from a 10% price change. Cut the variable cost by $5 and you get exactly the same effect. Trying to fix a loss by selling more, without touching either side of that gap, is running faster in the same direction.
When there is no break-even point at all
If the price is at or below the variable cost, the contribution margin is zero or negative and there is no break-even point. This is not an edge case for the sake of tidiness — it is the most important thing a break-even calculator can tell you, and most of them get it wrong.
Divide fixed cost by a zero margin and the arithmetic returns infinity. Divide by a negative one and it returns a negative quantity: with $12,000 of fixed cost and a price $2 below variable cost, the formula produces −6,000 units. A tool that prints that number is telling a business owner something that looks like a target. The truth is that at a negative margin every sale digs the hole deeper, and the more successful the marketing campaign, the faster the money disappears.
This calculator refuses to produce a figure in that situation and shows what would have to change instead: the price the unit would need to reach, or the variable cost it would have to fall to. Selling below variable cost can be a deliberate short-term choice — a loss leader, an introductory offer, clearing dead stock — but it should be a decision made with open eyes, not a number quietly divided.
Percentage costs are not per-unit costs
Some variable costs are a fixed amount per unit: the fabric, the box, the courier label. Others are a percentage of the selling price: card processing, marketplace commission, sales commission, revenue-based taxes, and percentage rent in a shopping centre. The two look similar in a spreadsheet and behave completely differently as soon as the price changes.
A 2.9% payment fee on a $100 sale is $2.90. On a $200 sale it is $5.80. If you entered it as "$2.90 per unit" when you were selling at $100, your break-even is silently wrong the moment you raise the price — and it errs in the dangerous direction, telling you the margin is fatter than it is. That is why the percentage field in this tool is separate from the money-per-unit field and is applied to the price, not added to the unit cost.
It is also why the example this page opens with reports 421 units rather than the 400 a $30 margin would imply. The default includes a 2.9% card fee, which is $1.45 on a $50 sale; the margin drops to $28.55 and the volume you need climbs by 21 units. A fee most people round to nothing is worth five percent of the target.
Percentages also stack. A seller taking cards at 2.9%, paying a 5% sales commission and handing 15% to a marketplace is losing 22.9% of every sale before a single physical cost is counted. Read as a contribution margin, that means the margin ratio can never exceed 77.1% no matter how cheap the product is to make — and that ceiling is often what decides whether a channel is viable at all.
Break-even with a profit target
Break-even is rarely the actual goal. The real question is usually "how much do I have to sell to make $6,000 this month?", and the answer uses the same division with the target added to the fixed cost: (fixed cost + target profit) ÷ contribution margin.
A profit target behaves exactly like extra fixed cost — money that has to be covered before you are satisfied rather than before you are solvent. So it shifts the required volume by target ÷ margin units, which is worth internalising: at a $30 margin, every $3,000 of desired profit costs another 100 units of sales, regardless of how big the fixed cost already is. If that extra volume is not realistic in your market, the margin has to change, because the target will not reach itself.
The same rearrangement answers the inverse question. Given a volume you are confident you can sell, the profit is volume × margin − fixed cost. Anyone writing a business plan should run that both ways: what the plan needs, and what the market plausibly gives.
Accounting, cash and economic break-even
There are three break-even points, and they answer different questions. Confusing them is how a business shuts down a product that was still paying its way, or keeps one that was quietly destroying value.
| Type | Fixed cost used | Question it answers |
|---|---|---|
| Accounting | All fixed costs | When does the income statement show zero? |
| Cash | Fixed costs minus depreciation | When does the bank balance stop falling? |
| Economic | Fixed costs plus a required return on capital | When does the business beat leaving the money elsewhere? |
Depreciation is a real cost of a machine wearing out, but it is not cash leaving the account this month — the money left when the machine was bought. Excluding it gives the cash break-even, which sits below the accounting one and is the number that matters when the question is whether you can survive the next quarter. Below the cash break-even you are burning money you actually have; between the two you are shrinking on paper while the account holds.
The economic break-even goes the other way. Capital tied up in the business could be earning a return somewhere else, and that opportunity cost is real even though no invoice arrives for it. Add the return you require to the fixed cost and the break-even rises. A business sitting between the accounting and economic points is profitable and still the wrong use of the money.
Margin of safety and operating leverage
Once you know the break-even point, the distance between it and what you actually expect to sell is the margin of safety — expressed in units, or as a percentage of expected sales. Expecting 500 units against a break-even of 400 gives a margin of safety of 100 units, or 20%: sales can fall a fifth before the business stops covering its costs.
That single percentage says more about fragility than any profit figure. Two businesses can report the same profit while one is running at a 40% margin of safety and the other at 5%; the second is one slow month from trouble. It is also the fastest way to sanity check a forecast, because a plan that only works at 97% of its projected volume is not a plan.
Operating leverage is the same idea from the other side. It measures how much profit swings for a given swing in sales, and equals total contribution margin divided by profit. At 500 units with a $30 margin and $12,000 of fixed cost, leverage is 5: a 10% fall in sales cuts profit by 50%. High fixed costs and fat margins produce high leverage, which is wonderful when volume rises and brutal when it falls — and it is exactly why businesses close to their break-even point feel so much more volatile than their revenue suggests.
More than one product: the weighted average margin
Most businesses sell several things with different margins, and there is no single break-even quantity for a mixed basket — 400 units means nothing if a unit might be a coffee or a cake. What exists instead is a break-even for a given sales mix.
The standard approach is a weighted average contribution margin: weight each product's margin by its share of unit sales, then divide the fixed cost by that average to get the total units, and split them back across products in the same proportions. Where the mix is unstable, use margin ratios and work in revenue instead: fixed cost divided by the weighted average contribution margin ratio gives break-even revenue directly.
The catch is that the answer only holds while the mix holds. Sell the same total volume with more of the low-margin item and the break-even point moves up without a single price or cost changing. This is why cafés push pastry with coffee and why cinemas care more about the concession stand than the ticket. Run this calculator per product, or on the average product you actually sell, and re-run it when the mix shifts.
What this model assumes, and where it stops
Break-even analysis is a straight-line model, and its assumptions are worth stating. The price is assumed constant at every volume, ignoring the discounts that usually come with bigger orders. The variable cost per unit is assumed constant too, ignoring both bulk purchasing savings and the overtime that appears when you push capacity. Fixed costs are assumed to stay fixed — but they are only fixed within a range, and a second shift, a bigger unit or another van makes them jump in a step. And everything produced is assumed to be sold, with no inventory build-up in between.
Within its range the model is still the most useful arithmetic in small business finance, because it converts vague worry into a number you can test against reality: can we plausibly sell that many? None of the figures you type here leave your browser — there is no account, no upload and nothing stored.
Frequently asked questions
What is the break-even formula?
Units to break even equal fixed cost divided by the contribution margin per unit, where the contribution margin is the selling price minus the variable cost of one unit. In revenue terms it is fixed cost divided by the contribution margin ratio, which gives the same answer multiplied by the price. Everything else in break-even analysis — profit targets, margin of safety, operating leverage — is a variation on that single division.
What if the price is lower than the variable cost?
Then there is no break-even point at all, and the calculator says so instead of printing a number. With a negative contribution margin every additional sale makes the loss bigger, so no volume rescues the business. The arithmetic would return a negative quantity, and a negative break-even is not a smaller target — it is a signal that the formula no longer applies. The only fixes are raising the price above the variable cost or cutting the variable cost below the price.
How do card fees and sales commissions fit in?
They are variable costs, but they scale with the price rather than with the unit, so they belong in the percentage field rather than the per-unit one. A 2.9% processing fee costs 29 cents on a $10 product and $2.90 on a $100 one. Entering it as a fixed amount per unit is right only at the single price where you happened to work it out, and drifts further from the truth every time you change the price.
How many units do I need for a specific profit?
Add the profit you want to the fixed cost and divide by the contribution margin: (fixed cost + target profit) ÷ contribution margin. A profit target behaves exactly like extra fixed cost, so it shifts the break-even point by target profit ÷ contribution margin units. On a $30 margin, every $3,000 of profit you want costs another 100 units of sales.
What is a good margin of safety?
It depends on how volatile your sales are, but the number itself is easy to read: it is the percentage your expected sales can fall before you stop covering your costs. Below about 20% a single slow month puts you under water, and anything under 10% means the plan only works if nothing goes wrong. A high margin of safety is what lets a business survive a bad quarter without borrowing.
Does the break-even point include tax?
It includes any tax that behaves like a cost of trading. Taxes charged as a percentage of revenue belong in the percentage field, alongside card fees and commissions, because they rise with every sale. Corporate income tax on profit does not belong in the calculation at all: at the break-even point profit is zero, so tax on profit is zero too, and adding it would move a point that by definition is not affected by it.