According to the WSJ Market Data Group, the S&P 500 
average correction lasts 51 trading sessions 
according to the data, although more recent ones have proved to be more short lived. The last five corrections have only lasted an average of 37 trading days, while going back to 1980, the average length has been 44 sessions. (Since 1950, the average lasted for 61 trading days.) The data doesn’t include corrections that expand into a bear market, or a 20% drop from a peak.

According to Bespoke Investment Group, which analyzed the 95 corrections the S&P has seen since 1928, the median decline for an S&P decline is 16.4%.

There is some good news for those who want to play the odds. Since World War II, according to data from Goldman Sachs, there have been 36 S&P 500 corrections. Of those, 24 didn’t presage the start of a recession. Furthermore, of the 24 corrections that didn’t coincide with a recession, 20 of them didn’t lead to a bear market. In the corrections that didn’t turn into bear markets, the median decline for the benchmark U.S. index was a drop of 13%.