An oscillator running from 0 (close at the range high) down to -100 (close at the range low). Readings above -20 are usually called overbought, below -80 oversold.
Williams %R is a momentum oscillator that shows where the current close sits inside the recent high-low range, on a 0 to -100 scale. Values near 0 mean price is closing near the top of its range (overbought); values near -100 mean it is closing near the bottom (oversold).
How it works
Over a rolling window (the period, default 14 bars) it finds the highest high and lowest low, then measures how far below the high the current close has settled. A close at the very top reads 0; a close at the very bottom reads -100.
Configuration
periodscalar
How many bars define the high-low range the close is measured against. Larger = smoother and slower; smaller = faster and noisier. 14 is the classic default.
Connects to
Feeds into
Examples
Filter: only allow shorts when Williams %R is above -20 (price stretched to the top of its range).
Wait for %R to climb back above -80 before taking a long in an uptrend.
Common mistakes
Confusing the inverted scale — values near 0 are overbought, not oversold.
Treating -20/-80 as automatic reversal signals; in a trend %R can hug an extreme for a long time.