What the Alligator indicator is
The Alligator is a trend indicator created by Bill Williams. It draws a set of smoothed moving averages on the price chart. A moving average is a line that shows the average price over a chosen number of bars.
Williams named the lines after parts of a mouth:
- Jaw (blue): the slowest line, with the longest period and the largest forward shift.
- Teeth (red): the middle line.
- Lips (green): the fastest line, with the shortest period and the smallest shift.
Williams described the market this way. When the lines are twisted together, the Alligator is "sleeping" and price is moving sideways. When the lines separate and fan out in order, the Alligator is "eating" and a trend is under way. When they start to come back together, it is "sated" and the move may be fading.
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Formula and default settings
Each line is a smoothed moving average (SMMA) of the median price. The median price is the midpoint between a bar's high and low. In MetaTrader this smoothing method is called "Smoothed".
The SMMA reacts slowly. Each new value moves only part of the way from the previous value toward the latest price:
SMMA(now) = SMMA(previous) + (Median price − SMMA(previous)) / N
N is the period of the line. A longer period makes the line smoother and slower to respond.
Each line is also shifted forward by a set number of bars, so it is drawn to the right of the latest candle. Because the shifted lines extend past the current candle, the gap between price and the lines is easier to see.
The default periods and shifts were set by Williams, and MetaTrader loads them when you add the indicator. You can see the current values in the settings window. The jaw always has the longest period and largest shift, and the lips the shortest of both.
How to add the Alligator in MT4 and MT5
The steps are the same on both platforms:
- Open a chart.
- Go to Insert → Indicators → Bill Williams → Alligator. You can also drag it from the Navigator window.
- In the settings window, check the period and shift for each line, the MA method (Smoothed) and the price used (Median Price).
- Change the colours if you want, then confirm.
For platform guides, see MetaTrader 4 and MetaTrader 5. If you want to try the indicator without risking money, Exness offers a demo account.
How to read it: a drawn example
The sketch below is drawn by hand and does not show real prices.
- Lines tangled: no clear direction. Many traders treat this as a range.
- Lips above teeth above jaw, with space between them: the market is in an upward trend. The reverse order means a downward trend.
- Lines narrowing after a run: momentum is slowing. This does not prove the trend has ended.
Williams used the Alligator together with Fractals, the Awesome Oscillator and the Gator Oscillator. The Gator shows the distance between the Alligator lines as a histogram.
Typical uses
- Trend filter: checking whether the lines are in order before studying market trends more closely.
- Range filter: treating tangled lines as a reason to stay out of trend-following setups.
- Trailing reference: watching the teeth or the jaw as a rough guide to where a trend weakens.
None of these uses is a signal. The indicator only describes past price.
Where the Alligator misleads
- Lag: SMMA lines are slow, and the forward shift does not make them predict anything. A move can be largely over by the time the lines fan out. See leading vs lagging indicators.
- Choppy markets: in a wide, noisy range the lines can separate briefly and then tangle again. This is a common source of false trend readings, similar to failed moving average crossovers.
- News spikes: a sharp bar shifts the median price, and the lines react late and unevenly.
- Timeframe conflict: the lines can show "eating" on a lower timeframe while a higher timeframe is still in a range. Compare them using multiple timeframes.
Parameter choices for experienced traders
- Shorter periods react faster but produce more false separations. Longer periods filter out noise but add lag.
- Keep the order: jaw slowest, lips fastest. If the periods overlap, the lines stop describing anything meaningful.
- Removing the shift draws the lines on current bars. This makes it easier to compare them with other moving averages, but it changes the indicator from Williams' design.
- To confirm trend strength, traders often add the ADX. To size stops based on volatility, they use the ATR.
Test any change on historical data and on a demo account before using it. Leveraged forex and CFD trading can lose money fast, and no setting removes that risk. See risk management and the wider technical analysis section.
Frequent questions
What are the Alligator indicator settings?
Each line has a period and a shift, and all of them use the Smoothed method on the median price. MetaTrader loads Williams' default values when you add the indicator. Check them in the settings window.
Is there a reliable alligator indicator strategy?
No indicator works in every market. The Alligator describes past price and can give false readings in ranges and after news.
Why are the lines drawn ahead of price?
Each line is shifted forward by its set number of bars. The shift is part of how the lines are displayed. It is not a forecast.
Does the Alligator repaint?
Past values of the lines do not change. The value on the forming bar moves until that bar closes.
Is the Williams Alligator the same as the Gator Oscillator?
No. The Gator Oscillator is calculated from the Alligator and shows the distance between its lines as a histogram.