The Stochastic Oscillator compares where a security's price closed relative to its trading range over the last x-time periods.

The formula for the %K parameter of the Stochastic is:

(today's close)-(lowest low %k periods)/(highest high %k periods)-(lowest low %k periods)

For example, to calculate a 10-day %K: First, find the security's highest high and lowest low over the last 10 days. For this example, let's assume that during the last 10 days the highest high was 46 and the lowest low was 38--a range of 8 points. If today's closing price was 41, %K would be calculated as:

41-38/46-38=3/8 = 0.375

The 0.375 in this example shows that today's close was at the level of 37.5% relative to the security's trading range over the last 10 days. If today's close was 42, the Stochastic Oscillator would be 0.50. The 0.50 would show that the security closed today at 50%, or the mid-point, of its 10-day trading range.

The Stochastic Oscillator always ranges between 0% and 100%. A reading of 0% shows that the security's close was the lowest price that the security has traded during the preceding x-time periods. A reading of 100% shows that the security's close was the highest price that the security has traded during the preceding x-time periods.