What is the Parabolic SAR Indicator?
The Parabolic SAR (Stop and Reverse) is a technical analysis indicator developed by J. Welles Wilder Jr., the same creator of the RSI and ADX indicators. It's designed to identify potential reversals in the price direction of traded assets and provide trailing stop-loss levels for trend-following strategies.
The indicator appears as a series of dots placed either above or below the price bars on a chart. When the dots are below the price, it indicates an uptrend and suggests holding long positions. When dots appear above the price, it signals a downtrend and suggests holding short positions or staying out of the market.
How is Parabolic SAR Calculated?
The Parabolic SAR calculation uses an iterative formula that incorporates the Acceleration Factor (AF) and Extreme Point (EP):
Where:
- SAR(n) = Current SAR value
- SAR(n+1) = Next period's SAR value
- AF = Acceleration Factor (starts at 0.02, increases by 0.02 each time a new extreme is made, up to 0.20)
- EP = Extreme Point (highest high in an uptrend, lowest low in a downtrend)
Key Rules for SAR Calculation
- In an uptrend: SAR cannot be above the prior two periods' lows. If calculated SAR is higher, use the lowest of those two lows instead.
- In a downtrend: SAR cannot be below the prior two periods' highs. If calculated SAR is lower, use the highest of those two highs instead.
- Trend reversal: When price crosses the SAR, the trend reverses. The new SAR starts at the previous EP, and AF resets to the initial value.
Understanding the Acceleration Factor (AF)
The Acceleration Factor is what gives the Parabolic SAR its characteristic "parabolic" shape. It controls how quickly the SAR converges toward the price:
| Parameter | Standard Value | Effect |
|---|---|---|
| Initial AF | 0.02 | Starting sensitivity level |
| AF Step | 0.02 | Increment when new extreme is reached |
| Maximum AF | 0.20 | Cap to prevent over-sensitivity |
Higher AF values make the SAR more sensitive and closer to price, which can result in earlier signals but also more whipsaws. Lower values create a more distant SAR that gives trades more room to breathe but may exit later.
Using Parabolic SAR as a Trailing Stop
One of the most popular uses of Parabolic SAR is as a dynamic trailing stop-loss:
- For long positions: Place your stop-loss at the SAR value below the price. As the trend continues and SAR rises, move your stop up accordingly.
- For short positions: Place your stop-loss at the SAR value above the price. As the trend continues and SAR falls, move your stop down accordingly.
- Exit signal: When price crosses the SAR, it's a signal to exit the current position and potentially reverse.
Parabolic SAR Trading Strategies
1. Basic Trend Following
Enter long when SAR flips below price (dots move from above to below). Enter short when SAR flips above price. Use SAR as your trailing stop throughout the trade.
2. SAR with ADX Filter
Combine Parabolic SAR with ADX to filter out weak signals. Only take SAR signals when ADX is above 25, indicating a strong trend. This helps avoid whipsaws during ranging markets.
3. Multiple Timeframe Confirmation
Use SAR on a higher timeframe to determine the overall trend direction, then use SAR on a lower timeframe for entry timing. Only take trades in the direction of the higher timeframe trend.
Limitations of Parabolic SAR
- Sideways markets: SAR generates many false signals during consolidation or ranging periods, leading to whipsaws and losses.
- Late reversals: The indicator may give late signals at major trend reversals, causing traders to give back significant profits.
- No magnitude indication: SAR only shows direction, not the strength or potential magnitude of a move.
- Parameter sensitivity: Results can vary significantly based on AF settings, requiring optimization for different markets and timeframes.
Frequently Asked Questions (FAQ)
What is the best AF setting for Parabolic SAR?
The standard settings (0.02 initial, 0.02 step, 0.20 max) work well for most markets. For faster-moving assets like crypto, consider higher values (0.025-0.03). For slower markets or longer-term trading, lower values (0.01-0.015) may reduce whipsaws.
Can Parabolic SAR be used for day trading?
Yes, but it works best on trending days. On choppy or ranging days, SAR will generate many false signals. Combine with volume or momentum indicators to filter trades, and consider using higher AF values for faster signals on intraday charts.
How does Parabolic SAR compare to moving averages?
Unlike moving averages that provide a single line, SAR provides specific price levels for stops. SAR is more adaptive—it accelerates as trends extend. However, moving averages are generally smoother and less prone to whipsaws in ranging markets.
What data format does this calculator accept?
Enter High, Low, Close values separated by commas or spaces, with each period on a new line. You can copy data directly from Excel, Google Sheets, or TradingView exports. The format is: High, Low, Close per line.