Donchian Channels: Highest High and Lowest Low Bands

Key Takeaways

• The upper rail equals the highest high of the last N bars; the lower rail equals the lowest low.
• Donchian's original four-week rule used N equal to 20 trading days for entries and exits.
• The Turtle system layered a 20-day entry channel with a 10-day exit channel for risk control.
• The most common mistake is buying every channel break without a trend or volatility filter.

What It Is

A Donchian channel is built from two simple statistics over a lookback window. The upper line is the highest high; the lower line is the lowest low. The midline is the average of the two. Unlike Bollinger or Keltner channels, no moving average and no volatility statistic feeds the construction.

Donchian's four-week rule said to buy when price closes above the four-week high and sell short when price closes below the four-week low. Dunn and Hargitt Financial Services rated it the best of the popular systems in their 1970 study, and the Turtles built their training program around the same idea.

The Intuition

Markets that trend tend to make new highs in uptrends and new lows in downtrends. If you cannot decide whether you are in a trend, a simple test is whether price is making N-day highs or N-day lows. Donchian channels turn that test into a visual.

The lookback window is the dial. A 20-day Donchian channel asks whether the asset is breaking out of its monthly range. A 55-day Donchian channel asks the same question on a quarterly scale. Longer windows produce fewer breakouts but cleaner trends.

How It Works

The Donchian channels indicator formula is:

upper_t  = max(high) over last N bars including bar t
lower_t  = min(low)  over last N bars including bar t
middle_t = (upper_t + lower_t) / 2

Most platforms offer a variant that excludes the current bar to prevent the channel from absorbing the breakout you are trying to trade. Backtests should be explicit about which variant is used.

Entry and exit logic in classical systems is symmetric. Go long on a close above the N-day upper rail; go short on a close below the N-day lower rail. Exit on the opposite signal or on a shorter Donchian channel break, depending on the system. The Turtles used 20-day entry and 10-day exit channels for System 1, and 55-day entry and 20-day exit channels for System 2.

Worked Example

Take a stock with these characteristics over the past 20 trading days: highest high of 105.00, lowest low of 92.00. The upper Donchian rail sits at 105.00, the lower at 92.00, and the midline at 98.50.

Today the stock closes at 105.50, a new 20-day high. A long entry triggers at the open of the next bar in a classical Donchian system. Position size is set by ATR so that a one-ATR adverse move costs a fixed percentage of capital, say 1 percent.

Suppose ATR is 2.00 and the stop is 2 ATR below entry, so 105.50 minus 4.00 equals 101.50. Two weeks later price has rallied to 112.00 and pulled back. The trailing exit is a close below the 10-day lower rail, which has risen to 103.00 as old low bars dropped out. A close at 102.50 closes the trade at roughly 102.50, locking in around 7 points of profit. The next 20-day breakout starts a fresh cycle.

Common Mistakes

1. Trading every breakout without a filter. Most assets spend half their lives in ranges, and most range breakouts fail. A trend filter such as a 200-day moving average or an ADX threshold cuts the worst of these.
2. Forgetting whether the current bar is included. A channel that includes the current high will always equal that high when price prints a new extreme, so the breakout signal is by construction. Most backtests want the prior-bar version.
3. Using the same N on every asset. A 20-day channel on the S and P 500 is not equivalent to a 20-day channel on a small-cap stock. The right window depends on the average length of the asset's trends.
4. Skipping a separate exit channel. Trading 20-day entries and 20-day exits gives back too much profit. The Turtles separated the entry lookback from the shorter exit lookback for a reason.
5. Confusing Donchian with price channels. Some platforms label their fixed-percentage channels as price channels and Donchian as a distinct overlay; others use the names interchangeably. Check the formula on your charting tool.

Frequently Asked Questions

What is the Donchian channels indicator in simple terms? The Donchian channels indicator draws lines at the highest high and lowest low over a chosen number of bars. A close above the upper line is a breakout signal; a close below the lower line is a breakdown signal.

How does the Donchian channels indicator affect investment decisions? Systematic trend-followers use it to define entries and stops with no parameter beyond the lookback length. Discretionary traders use it as a structural reference for where breakout buyers and breakdown sellers cluster.

What is a real-world example of the Donchian channels indicator? The Turtle Traders' two systems used 20-day and 55-day Donchian breakouts as entries with shorter Donchian channels as exits. Both systems produced strong long-term results across commodities, currencies, and bonds in the 1980s and 1990s.

How can investors use the Donchian channels indicator effectively? Pick a lookback long enough to filter range noise, use a shorter channel for exits, and pair entries with a higher-timeframe trend filter. Size positions by ATR so risk is constant across regimes.

How are Donchian channels different from Bollinger Bands? Donchian channels are price-extreme bands; Bollinger Bands are statistical bands around a moving average. Donchian rails only move when a new high or low prints, while Bollinger rails move every bar with the average and standard deviation.

Sources

1. StockCharts ChartSchool. Donchian Trading Guidelines. https://chartschool.stockcharts.com/table-of-contents/overview/donchian-trading-guidelines
2. StockCharts ChartSchool. Price Channels. https://chartschool.stockcharts.com/table-of-contents/technical-indicators-and-overlays/technical-overlays/price-channels
3. Lizard Indicators. Donchian Channel Strategy (Turtle System). https://www.lizardindicators.com/donchian-channel-strategy/
4. IncredibleCharts. Donchian Channels. https://www.incrediblecharts.com/indicators/donchian_channels.php

Disclaimer

This article is educational content only and is not financial advice. Nothing here is a recommendation to buy, sell, or hold any security. Consult a licensed advisor before making investment decisions.