Parabolic SAR explained

Trend

What Parabolic SAR measures

Parabolic SAR (Stop and Reverse) places dots above or below price to indicate trend direction and potential stop-loss levels. Dots below price = uptrend; dots above = downtrend. When price crosses the dots, the SAR 'reverses' — it flips to the other side. It's designed as a trailing stop and reversal signal in trending markets.

How Parabolic SAR readings are interpreted

In an uptrend, the dots below price trail upward, showing where a trailing stop could be placed. As the trend accelerates, the dots move faster toward price (due to the acceleration factor). When price hits the dots, the trend is considered reversed. The signal is simple and visual.

Conventional Parabolic SAR levels

Dots below price: uptrend — hold longs, trail stops at dot level
Dots above price: downtrend — hold shorts or stay flat
SAR flip (dots cross price): trend reversal signal
Rapid dot acceleration: strong trend gaining momentum
Dots very close to price: potential imminent reversal

Where Parabolic SAR works, and where it does not

Performs best in trending markets. In ranging/choppy markets, SAR flips repeatedly — rapid alternating dots above and below price signal a ranging environment. When SAR flips more than two or three times in a 10-bar window, its readings are generally considered unreliable.

Indicators commonly read alongside Parabolic SAR

ADX: Parabolic SAR signal + ADX > 25 = confirmed trend reversal
Supertrend: Both SAR and Supertrend agreeing = double trend confirmation
EMA: SAR flip above 200 EMA = trend reversal with long-term support

Known limitations of Parabolic SAR

In choppy markets, SAR generates frequent false reversals (whipsaws)
The default 0.02 acceleration factor creates too many signals in volatile assets — increase to 0.03-0.05 for crypto
SAR can only catch trends — it will never catch a bottom or top precisely

Parabolic SAR in practice

Conventionally used as a trailing stop rather than in isolation
SAR reversals are conventionally given more weight when ADX is above 20 (trending market confirmed)
For crypto: increase the step (acceleration) to 0.03 to reduce whipsaws
A SAR flip is conventionally read alongside a confirming momentum indicator such as a MACD crossover

Other trend indicators

Detrended Price Oscillator
Random Walk Index
Alligator
ADX — Average Directional Index

Testing ideas built on Parabolic SAR

A reading of Parabolic SAR can be written as an exact rule and checked against historical data — as a full strategy with entries, exits and costs, or as a single condition and what followed it:

How to backtest a trading strategy without code
Event analysis: what follows a market event

Plot it yourself. Add this indicator to a chart, change every parameter and watch the line move, then backtest how the rule would have behaved on historical data — free on the S&P 500 ETF, no card.

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This is reference material, not advice. It describes what each indicator measures and how its readings are conventionally interpreted. Nothing here is a recommendation to buy or sell anything, and no indicator predicts future prices. GU Analyser is an analytical tool — no money is ever traded here.