In economics, the difference between actual and potential GDP is called the output gap.
Potential GDP is an estimate of the level of real production an economy could sustain over the long term with its labor, capital, technology, and institutions. The output gap compares that estimate with actual GDP, often as a percentage of potential GDP: (actual GDP − potential GDP) ÷ potential GDP × 100.
A negative output gap means the economy is producing below estimated capacity and is often associated with weak demand and elevated cyclical unemployment. A positive gap, sometimes called an inflationary gap, means actual output is above estimated potential and may coincide with rising price pressure. The measure is useful but imperfect because potential GDP cannot be observed directly and must be estimated. “Recessionary gap” and “inflationary gap” describe possible signs of the output gap, not its general name.