Break-even Analysis

Break-even analysis finds the point at which revenue exactly covers costs: below it a business loses money, above it every extra sale adds profit. In units, the break-even point is fixed costs divided by the contribution margin per unit, which is the selling price minus the variable cost of one more unit. In revenue terms, it is fixed costs divided by the contribution margin ratio.

The number on its own is less useful than the gap around it. The distance between the sales a business expects and the sales it needs to break even is its margin of safety: how wrong the forecast can be before the losses start. A business with high fixed costs and low variable costs has a high break-even point and a thin margin of safety, but once it is past the line, most of each extra dollar of revenue becomes profit. That trade is called operating leverage, and it cuts both ways.

Airlines live on that edge. In May 2020, from a sample of 122 airlines, IATA found that carriers broke even, on average, at a load factor of 77%: more than three seats in four had to be sold before a flight made money, and only four airlines in the sample could break even below 62%. That is why IATA concluded that leaving middle seats empty for social distancing, which would cap load factors at about 62%, would make most airlines financially unviable. The break-even point turned a public-health rule into a solvency question.

The low-cost carriers answer by pushing the line down. Ryanair, which calls itself Europe's largest airline group, carried 183.7 million passengers in the year to March 2024, and it charges separately for almost everything beyond the seat. That ancillary revenue now makes up about a third of its total revenue, a second income stream that lets it sell the seat itself for less and still break even.

Break-even reading also exposes where profit really comes from. Tesla reported net income of $721 million for 2020, its first profitable year, but it also booked $1.58 billion of revenue from selling regulatory credits to other carmakers. Take the credits away and Tesla had not yet crossed the line. Amazon, which went public in May 1997, did not report a profitable year until 2003, when it earned $35 million; its first letter to shareholders had warned that it would make investment decisions "in light of long-term market leadership considerations rather than short-term profitability considerations."

Software companies run the same arithmetic customer by customer. Instead of a single break-even point they track CAC payback, the months it takes a customer's gross profit to repay the cost of acquiring them. Bessemer Venture Partners suggests that cloud companies selling to small businesses should aim to recover it in under 12 months.

The basic model has limits. It assumes costs and prices move in straight lines, treats every unit as identical, ignores the time value of money and describes a single moment. Its value comes from running it more than once: changing the price, the cost structure or the mix and watching how far the line moves shows which assumption the business can least afford to get wrong.