Average true range

Average one-minute bar range in dollars, counting gaps: higher means the price is moving more.

ATR measures how far a bar typically travels. For each one-minute bar it takes the true range: the high-low range, widened to include any gap from the previous bar's close, so a bar that gaps away from the last close counts that gap too. The line is the average of those ranges over the window, seeded as a simple mean of the first N bars and then smoothed with Wilder's method, so each new bar moves it by only 1/N of the difference. The output is in price units: on the SPY sample a typical one-minute ATR was about 14 cents.

How to read it

The line sits in its own pane below the price, in dollars, and stays blank until the first full window of bars.
A rising line means bars are widening; a falling line means the market is calming down.
A burst of wide bars lifts the line, which then decays slowly over the window instead of snapping back.
The 0.14 line is the median ATR over the sample; the shaded zone above 0.35 holds the top 5% of readings.

What it outputs

ATR: Average true range in dollars: the typical one-minute move, gaps included, smoothed over the window.

Settings

Window: How many bars the average covers. Raising it makes the line smoother and slower to react to a burst of wide bars; lowering it tracks recent bar ranges more tightly and swings more on single bars.

Pitfalls

The value is in dollars, not percent: on this sample the median was about 0.018% of the close, so compare across symbols or prices by dividing by close.
Each new bar moves the average by only 1/window of the gap, so after a spike the line stays high for many bars and lags the current move.
ATR gives the size of moves, not their direction; a high reading does not say which way price will go.