Williams Percentage Range, or Williams %R is a momentum indicator similar to Stochastic indicators and again is concerned with determining overbought and oversold levels.

%R = (highest high over x periods – close) / (highest high over x periods – lowest low over x periods) * -100

The range is from 0 to -100 with above -20 = overbought, and below -80 = oversold.

Commonly, Williams %R is calculated using 14 periods and can be used with any time frame. The diagram shows 2 Williams %R plots, using 14 periods (green) and 28 periods (blue).

In practice, as shown, the 14-period %R can be bit jumpy, to say the least – and it requires a fair amount of caution not to be set off by its whipsaws. The 28-period is a calmer sort of guy…

Always remember that overbought doesn’t necessarily = sell now and vice-versa with oversold. The overbought period can continue without reversal, so looking at signals of reversal becomes important eg. waiting for the Williams %R to cross -50 as a confirmation.