Output Gap
The Output Gap is the difference between an economy's actual GDP and its estimated potential GDP, expressed as a percentage of potential GDP, indicating whether the economy is running above capacity (positive gap) or below capacity (negative gap) at a given point in time.
The output gap is one of the most important — and most contested — concepts in macroeconomics because it directly shapes inflation forecasts and monetary policy decisions. A positive output gap (actual GDP above potential) implies that the economy is overstimulated: labor markets are tight, capacity utilization is high, and inflationary pressures are building. A negative output gap implies slack: unemployment is elevated, factories are underutilized, and disinflationary or deflationary pressure may be present.
The challenge is that potential GDP is not observable; it must be estimated using statistical filters (like the Hodrick-Prescott filter) or structural economic models. Different methods often produce meaningfully different estimates, and historical revisions to GDP data can change calculated output gaps substantially. The Fed and Congressional Budget Office each publish their own estimates, and they can diverge.
In practice, central banks use output gap estimates alongside inflation readings to judge whether policy is calibrated appropriately. During the recovery from the 2020 COVID recession, debate about the output gap was central to the Fed's 2021 decision to keep rates at zero: the Fed believed a significant negative gap existed and that inflation was transitory — a judgment that proved to be incorrect as supply-side disruptions and fiscal stimulus combined to drive inflation to multi-decade highs.
The output gap also influences fiscal policy. Keynesian economists argue that governments should run deficits to close negative output gaps (demand stimulus) and surpluses or balanced budgets when the gap is positive (to prevent overheating). The size of fiscal multipliers is theoretically larger when the gap is negative — idle resources are available to be mobilized by government spending.
For investors, output gap analysis provides a framework for thinking about the sustainability of corporate earnings growth, the inflation outlook, and the likely direction of monetary policy. Earnings tend to be strong when the economy runs above potential and compress when gaps turn deeply negative.