Alfred Kahn and the Marginal Cost of Your Next Customer

Alfred Kahn was a Cornell economist who in 1977 became chairman of the Civil Aeronautics Board and proceeded to dismantle it — overseeing the deregulation of the American airline industry with a theoretical rigor and a practical shrewdness that produced one of the most consequential economic policy changes of the 20th century. He is also the author of The Economics of Regulation, a two-volume work that remains the definitive treatment of the theory of regulated industries.

The concept that animates Kahn's airline work — and that I find most useful in thinking about SaaS and subscription pricing — is marginal cost pricing: the principle that in competitive markets, price tends toward marginal cost, and that the most efficient pricing is the one that reflects the actual cost of producing the next unit.

For software businesses, the marginal cost of the next customer is close to zero. The implications of this are more radical, and more frequently misunderstood, than most founders appreciate.

What marginal cost pricing actually means

In traditional manufacturing, marginal cost — the cost of producing one additional unit — is real and meaningful. The steel mill incurs real costs to produce each additional ton of steel. Pricing above marginal cost is possible only where there is some market power; in competitive markets, price is driven toward marginal cost by competition.

Kahn's contribution to airline economics was to recognize that the regulated fare structure bore no relationship to the actual marginal costs of flying different routes at different times. A seat on a half-empty plane has a marginal cost very close to zero — the plane is flying anyway, the incremental cost of an additional passenger is minimal. The regulated fare structure priced seats well above marginal cost, benefiting incumbent carriers at the expense of passengers who would have paid a lower price for the same product.

Deregulation allowed airlines to price toward marginal cost — which produced yield management, variable pricing, and the structure of the modern airline industry, with all its attendant complexity. Whether this was unambiguously good is debatable. That it was a more accurate reflection of the underlying economics is not.

For software businesses, the marginal cost of the next customer is close to zero. The strategic implications of this are more radical than most founders appreciate.

The SaaS application

A SaaS business has very high fixed costs — engineering, product, infrastructure, go-to-market — and very low marginal costs. The marginal cost of onboarding the next customer, once the product is built and the infrastructure is running, is close to zero. This creates a pricing structure that looks nothing like manufacturing: the first customer pays for a huge fraction of the total cost of building the product; the millionth customer is almost pure margin.

The strategic implications are enormous. A SaaS business that prices all customers the same, regardless of their volume, usage, or segment, is leaving most of the value on the table. A business that prices on actual value delivered — usage-based models, tier structures that reflect willingness to pay, enterprise pricing that captures the full value of a large deployment — captures the surplus that simple per-seat pricing does not.

Kahn's lesson applied: price toward marginal cost for the segments where the volume and competitive dynamics make that the right strategy (SMB, high-velocity self-serve), and price toward value for the segments where market power makes that possible (enterprise, mission-critical use cases). The two-tier pricing structure that most modern SaaS companies have arrived at — a freemium or low-cost entry tier and a premium enterprise tier — is an implicit application of Kahn's framework, whether or not the founders who designed it know his name.

The land and expand logic

The land-and-expand motion — enter at a low price point, expand as the customer's usage and dependency grows — is a direct application of the marginal cost principle. The initial contract is priced to reflect the low marginal cost of the first deployment. The expansion is priced to capture the value created by integration into the customer's workflow, the switching costs that have accumulated, and the incremental value of additional users or use cases.

Kahn would recognize this immediately: it's a form of price discrimination that captures consumer surplus at each stage of the relationship, moving from marginal-cost pricing at entry to value-based pricing at scale. The pricing structure follows the economics.

Alfred Kahn spent his career applying economic theory to the real-world pricing of industries where the relationship between cost and price had been distorted by regulation or convention. The insight — that pricing should reflect the actual economics of what you're selling, not convention or competitor behavior — is as applicable to SaaS pricing strategy as it was to airline fares in 1978. Know your marginal cost. Build your pricing from there.