**A standard U.S. rule of thumb suggests roughly 12% real GDP growth to halve unemployment in one year, or 7% annually over two years.** These are approximate calculations, assuming unemployment starts at 9–10%.

The relationship is called **Okun’s law**: each year, GDP growth about **2 percentage points above potential growth** is associated with a **1 percentage point decline in unemployment**. Potential growth accounts for rising productivity and a growing labor force; some growth is therefore needed simply to keep unemployment steady. [Federal Reserve explanation](https://www.federalreserve.gov/newsevents/speech/bernanke20120326a.htm)

Using the San Francisco Fed’s **2010 estimate of 2.5% annual potential growth**, the calculation is:

\[
\text{Required annual real GDP growth}
\approx 2.5\%+\frac{2(u_0-u_{\text{target}})}{T},
\]

where unemployment rates are expressed in percentage points and \(T\) is the number of years. [Janet Yellen’s February 2010 speech](https://www.frbsf.org/news-and-media/speeches/yellen-speeches/yellen-outlook-economy-monetary-policy/)

Assuming a starting date of December 2010:

| Target | Time available | Starting at 9%, targeting 4.5% | Starting at 10%, targeting 5% |
|---|---:|---:|---:|
| December 2011 | One year | 11.5% growth | 12.5% growth |
| December 2012 | Two years | 7.0% annually | 7.5% annually |

**Yes, policymakers made similar calculations at the time.** In May 2010, Boston Fed President Eric Rosengren estimated that reaching 5% unemployment by the end of 2013 would require real GDP growth averaging about 5% annually over the available period. [Speech and supporting slides](https://www.bostonfed.org/news-and-events/speeches/considering-the-routes-to-a-policy-destination.aspx)

These figures are conditional estimates, not guaranteed requirements. Okun’s law is an empirical relationship, and it deviated substantially during the Great Recession. Changes in productivity, hours worked, and labor-force participation can alter how much unemployment falls for a given amount of growth. [San Francisco Fed analysis](https://www.frbsf.org/research-and-insights/publications/economic-letter/2010/03/okun-law-unemployment-2009/)