GDP Gap Calculator (output gap: actual vs potential GDP)

Understanding the output gap calculator — concept and principle

This calculator finds the output gap, the percentage difference between an economy's actual real GDP and its potential GDP. It also shows actual output as a share of potential, the gap in money and whether the gap is recessionary or inflationary. Use it for macroeconomics courses and to understand discussions of slack in the economy and monetary policy.

The economy produces 300 less than its estimated potential: a gap of −1.26%.

How it is calculated

Output gap (%) = (actual real GDP − potential real GDP) ÷ potential real GDP × 100.
Actual as a share of potential = actual ÷ potential × 100.
Gap in output = actual − potential.
Negative gap: recessionary; positive gap: inflationary.

Use real (inflation-adjusted) GDP for both values.

The principle

Potential output is what the economy can produce at sustainable full use of its labour and capital. In the US the Congressional Budget Office publishes estimates of it. When actual output is below potential, workers and machines are idle: unemployment tends to be high and price pressures weak. When output is above potential, the economy runs hot, which tends to push inflation up. Central banks watch the gap when setting interest rates.

Worked example

Default inputs: actual real GDP 23,500, potential real GDP 23,800.

Gap in output = 23,500 − 23,800 = −300.
Output gap = −300 ÷ 23,800 × 100 ≈ −1.26%.
Actual as a share of potential ≈ 98.7%.
Type of gap: negative (recessionary).

Each point is the calculator re-run with only “Potential real GDP” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Potential real GDP	Output gap
5,950	294.96%
11,900	97.48%
17,850	31.65%
23,800	-1.26%
29,750	-21.01%
35,700	-34.17%
47,600	-50.63%

How to read the result

A gap of about −1% suggests modest slack. Gaps of several percent below zero are typical of recessions. A positive gap above about 1% often comes with rising inflation pressure. Because potential GDP cannot be observed directly, estimates are uncertain and are revised, so treat small gaps cautiously.

Common mistakes

Using nominal GDP, which mixes price changes with output.
Treating potential GDP as a ceiling that cannot be exceeded.
Reading a negative gap as negative growth; the economy can grow and still be below potential.
Comparing gaps based on different potential estimates.

Keep in mind: Potential GDP is an estimate with considerable uncertainty. Use official estimates for analysis. This is not financial advice.

Frequently asked questions

What is potential GDP?

The level of output the economy can sustain with full, non-inflationary use of its resources.

What does a negative output gap mean?

The economy produces less than it could, usually with higher unemployment.

Who estimates potential GDP in the US?

The Congressional Budget Office publishes the most widely used estimates.

Sources: S. A. Wolla, "Minding the Output Gap: What Is Potential GDP and Why Does It Matter?", Page One Economics, Federal Reserve Bank of St. Louis (May 2021)

Checked 9 Nov 2026. S. A. Wolla, “Minding the Output Gap: What Is Potential GDP and Why Does It Matter?”, Page One Economics, Federal Reserve Bank of St. Louis (May 2021): output gap = (actual − potential) ÷ potential × 100; CBO potential GDP.

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