Forex Indicators: Moving Averages, RSI and ATR (and Their Limits)

Technical indicators are calculations on past prices that summarise trend, momentum or volatility. The three most useful for forex beginners are the moving average (trend), the RSI (momentum) and the ATR (volatility, in pips). They help you describe the market consistently and set stops sensibly, but they do not predict the future, and any trading rule built on them must be tested after costs.

Moving averages: trend

A simple moving average (SMA) is the average closing price over the last N periods. An exponential moving average (EMA) gives more weight to recent prices, so it reacts faster.

Common uses:

• Trend filter: only take long trades when price is above the 200-day SMA, only shorts when below.
• Crossovers: the 50-day crossing above the 200-day (the "golden cross") as a buy signal, below it (the "death cross") as a sell signal.
• Dynamic support and resistance: some traders watch pullbacks to the 20 or 50 EMA in a trend.

Limits: moving averages always lag. A 200-day average reacts to a turn only after a large part of the move has happened. In ranges, crossovers generate repeated losing signals, called whipsaws. Faster averages lag less but whipsaw more.

RSI: momentum

The Relative Strength Index (RSI), introduced by J. Welles Wilder in 1978, compares average gains with average losses over a period, usually 14:

RSI = 100 − 100 ÷ (1 + RS), where RS = average gain ÷ average loss over the period

Traditional readings: above 70 is "overbought", below 30 is "oversold". In practice:

• In a strong trend, RSI can stay above 70 (or below 30) for weeks. Selling simply because RSI is high is a common way to fight a trend and lose.
• Very short RSI settings, such as RSI(2), are used in mean-reversion systems that buy short-term dips within a longer uptrend. They trade often, so spreads matter a lot.
• Divergence (price makes a new high, RSI does not) suggests weakening momentum but is not a timing signal on its own.

ATR: volatility in pips

The Average True Range (ATR), also from Wilder, measures how far a pair typically moves per period. For each candle, the true range is the largest of:

1. High − low
2. |High − previous close|
3. |Low − previous close|

ATR(14) is the average of the last 14 true ranges. Using the previous close captures gaps.

ATR's main uses:

• Stop distance: placing stops 1.5 to 3 × ATR away, so they sit outside normal noise.
• Position sizing: wider ATR → wider stop → smaller position, so every trade risks the same money. See Stop-Loss and Risk:Reward and Position Sizing.
• Filtering: avoiding trades when ATR is unusually low (dead market) or extremely high (news shock).
• Trailing stops: trailing a stop 2 or 3 × ATR behind price.

ATR does not tell you direction. A rising ATR can come with a rally or a crash.

Other indicators you will see

MACD (difference between two EMAs), Bollinger Bands (a moving average with bands two standard deviations away), stochastics and Ichimoku are all built from the same inputs: open, high, low and close. Adding more of them adds little new information and many ways to fool yourself. Most professionals keep their toolkit small.

The limits of indicators

Keep these points in mind:

1. Indicators repackage price. They cannot know about tomorrow's central bank decision.
2. Settings are not magic. If RSI(14) works but RSI(13) and RSI(15) fail, the result is probably luck.
3. Costs change everything. A rule with many small trades can look profitable before spreads and swaps and lose after them.
4. Markets change. A rule that suited one decade may not suit the next.

A practical starting kit

• Daily chart with a 50-day and 200-day moving average for trend.
• ATR(14) for stop distance and position size.
• Optionally RSI(14) to judge whether a move is stretched, never as a stand-alone signal.

With that, you can describe any pair in one line: "Above its 200-day average, ATR 80 pips, RSI 62, sitting just under resistance." Then fundamentals tell you why it might move, starting with Interest Rates and Central Banks.