Smoothing period
Also called Smoothing length, ADX smoothing, Slowing
A smoothing period is the number that sets how strongly an indicator averages its own raw readings into a calmer line: with simple smoothing it is the count of bars averaged, with Wilder or exponential smoothing it sets how big a step the line takes each bar. A higher number filters more noise but reacts later.
Many oscillators, such as ADX and Stochastic, have two kinds of number. One is a lookback that measures the market. The other is a smoothing period that averages the result. Changing the smoothing period changes when your signal shows up. That can move your entry by whole bars, and every bar can cost you pips.
What the smoothing period does to an oscillator line
An oscillator first calculates a raw reading on every bar. Raw readings jump around because one large candle can swing them hard. The smoothing period tells the indicator how strongly to blend these readings together before it draws the line you trade from. With simple smoothing, the period is just the count of bars averaged. With Wilder or exponential smoothing, the period sets how big a step the line takes toward each new reading, and older bars fade out slowly instead of dropping out after a fixed number of bars.
The chart below shows the same raw reading drawn twice: once as it is, and once smoothed over 5 bars. The raw line crosses 25 at bar 4 and falls back at bar 5. It crosses again at bar 6, drops at bar 7, and only stays above from bar 8. The smoothed line crosses once, at bar 9, and stays above.
Smoothing period in ADX
The ADX works this way. First come two lines: +DI tracks upward price movement and −DI tracks downward movement. The indicator builds a raw value called DX from the gap between +DI and −DI, divided by their sum. Then it averages DX over the smoothing period, and the result is the ADX line. Some platforms show this as one input. Others split it into a "DI length" (the lookback) and an "ADX smoothing" input. A bigger ADX smoothing makes the line slower to confirm a new trend and slower to show that one is fading.
The classic ADX uses Wilder's smoothing. Each bar, the line moves a fraction of the gap toward the new raw value:
New line = old line + (raw − old line) ÷ smoothing period
How a smoothing change shifts your entry: a worked example
The figures here are an illustrative example. Your ADX line sits at 20, and the raw DX suddenly holds at 40 as a trend starts. Your rule is to enter when ADX goes above 25. Compare a smoothing period of 5 with a period of 10.
With smoothing 10, your signal comes one bar later. Say you trade the 1-hour chart, and EUR/USD moves 15 pips in your direction during that extra bar. With a 0.10 lot (10,000 units), a pip is worth $1, so you give up 15 × $1 = $15 of the move. With 1 lot (100,000 units), you give up 15 × $10 = $150.
Now count the other side. Over the same stretch, smoothing 5 also gave two false starts that each stopped you out for 10 pips; smoothing 10 skipped them in this stretch. That is 2 × 10 = 20 pips lost with smoothing 5, against the 15 pips it gained by entering earlier. In this example, smoothing 10 comes out 20 − 15 = 5 pips ahead, or $5 at 0.10 lot and $50 at 1 lot. With fewer false starts, the result would flip in favour of smoothing 5.
Where you set the smoothing period
Open the indicator's settings or inputs window on your trading platform. The smoothing period has different names on different oscillators:
| Indicator | What the input may be called | What it smooths |
|---|---|---|
| ADX | ADX smoothing, period | The DX line |
| Stochastic | Slowing, %D period | Raw %K (Slowing), then %K into the %D line (%D period) |
| MACD | Signal period | The MACD line |
| Stochastic RSI | K and D smoothing | The raw Stochastic RSI value |
There may be a separate field for the smoothing method, such as simple, exponential or Wilder. Exponential gives the latest bars more weight, so it starts reacting sooner than simple at the same period. Wilder's method is the slowest of the three at the same number. Two charts with the same period can show different values if their methods differ.
Checks before you trade with a changed smoothing period
- Find out which number you are changing. Changing the lookback changes what the indicator measures. Changing the smoothing keeps the measurement but changes when, and whether, the line reaches your level.
- Use this decision rule. If signals often reverse within one or two bars, raise the smoothing. If your entries keep arriving after most of the move, lower it. Either way, first weigh the pips each extra bar of delay costs you against the pips lost on the false starts it filters out, as in the calculation above.
- Change one input at a time. Then you know which input caused the difference.
- Keep the method the same. Before you compare your chart with someone else's levels, check that the smoothing method matches.
- Look at the early history. A smoothed line needs a run of bars before its values settle. Ignore readings at the very start of the chart.
FAQ
Does a higher smoothing period make the ADX more reliable?
No. It makes the line steadier, not more correct. You get fewer false starts, but you see real trends and real reversals later.
Should I use a different smoothing period on a different timeframe?
Not by default. A bar is a bar to the formula. On a 4-hour chart, the same setting simply means a longer delay in hours. Decide based on how much delay in time and pips you can accept.
Can smoothing make an oscillator miss a signal completely?
Yes. A short burst can fade out before the smoothed line reaches your level. If your strategy depends on quick spikes, test a lower smoothing period on past charts first.