Key takeaways
- A simple moving average (SMA) gives equal weight to each price in the period; an exponential moving average (EMA) gives more weight to recent prices.
- All moving averages lag price because they are built from past data.
- Moving averages work best in trending markets and produce many false signals in ranges.
- Crossovers and slope can help describe a trend, but they do not predict where price will go.
Contents
A moving average smooths out price fluctuations by averaging prices over a set number of periods. Because it "moves" forward with each new candle, it gives a continuously updated view of the trend. Moving averages are among the most popular indicators in forex, and many other indicators, including MACD and Bollinger Bands, are built on them.
Simple moving average (SMA)
The SMA adds up the closing prices for the chosen number of periods and divides by that number.
SMA = (sum of the last N closes) ÷ N
Every price in the period carries the same weight. When a new candle closes, the oldest price drops out and the newest enters.
Worked example: a 5-period SMA
Assume, for illustration, these five EUR/USD daily closes:
| Day | Close |
|---|---|
| 1 | 1.0810 |
| 2 | 1.0825 |
| 3 | 1.0840 |
| 4 | 1.0830 |
| 5 | 1.0845 |
Sum: 1.0810 + 1.0825 + 1.0840 + 1.0830 + 1.0845 = 5.4150
SMA: 5.4150 ÷ 5 = 1.0830
Exponential moving average (EMA)
The EMA gives more weight to recent prices so it reacts faster to new information. It uses a multiplier based on the period length:
Multiplier = 2 ÷ (N + 1)
EMA today = (Close today − EMA yesterday) × Multiplier + EMA yesterday
The first EMA value is usually seeded with an SMA of the same length.
Worked example: a 10-period EMA
- Multiplier: 2 ÷ (10 + 1) = 2 ÷ 11 ≈ 0.1818
- Assume yesterday's 10-period EMA was 1.0830 and today's close is 1.0885.
- Difference: 1.0885 − 1.0830 = 0.0055
- Weighted difference: 0.0055 × 0.1818 ≈ 0.0010
- New EMA: 1.0830 + 0.0010 = 1.0840
The EMA moved 10 pips toward the new price in a single step. A 10-period SMA would move by (new close − the close that dropped out) ÷ 10, which depends on the old price leaving the window.
SMA vs EMA at a glance
| Feature | SMA | EMA |
|---|---|---|
| Weighting | Equal | More weight on recent prices |
| Reaction speed | Slower | Faster |
| False signals | Fewer, but later | Earlier, but more whipsaws |
| Common uses | Long-term trend (50, 100, 200) | Shorter-term trend (9, 12, 20, 26) |
How traders use moving averages
Trend direction
A rising average with price above it describes an uptrend; a falling average with price below it describes a downtrend. A flat average often signals a range.
Dynamic support and resistance
In trends, price sometimes pulls back to a moving average and then resumes. Traders treat the average as moving support or resistance. Like horizontal levels, these are zones of interest, not guaranteed turning points.
Crossovers
- When a shorter average crosses above a longer one, some traders read it as bullish. The 50-day crossing above the 200-day is often called a "golden cross".
- When a shorter average crosses below a longer one, it is read as bearish. The 50-day crossing below the 200-day is often called a "death cross".
Crossovers confirm a change that has already happened. By the time they occur, a large part of the move may be over.
The lag problem
Every moving average is calculated from past prices, so it always trails the market. Longer periods smooth more noise but lag more. Shorter periods react faster but produce more false signals. There is no setting that removes this trade-off, and no moving average predicts future prices. Test any approach in a risk-free environment, such as the Trading Simulator, before relying on it.
Common mistakes
- Using crossovers in a range. Sideways markets cause repeated, losing whipsaw signals.
- Optimizing settings endlessly. A period that fit the past perfectly often performs poorly in the future.
- Treating the average as an exact level. Price often slices through it slightly before turning, or does not turn at all.
- Ignoring context. A moving average signal against a major support or resistance area deserves extra caution.
Summary
Moving averages smooth price to reveal the trend. The SMA weights every price equally, while the EMA weights recent prices more and reacts faster. Traders use them for trend direction, dynamic support and resistance, and crossovers. All moving averages lag, work best in trends and fail in choppy markets. They describe what has happened, not what will happen. Next, the RSI indicator looks at momentum rather than direction.
Glossary terms in this lesson
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Practice worksheet
Practice worksheet
4 exercises to try on paper. Print it, save it as a PDF from the print dialog, or download a plain-text copy.
- Calculate the 3-period SMA of these closes: 1.2710, 1.2740, 1.2770.
- Calculate the EMA multiplier for a 20-period EMA using 2 ÷ (N + 1). Round to four decimal places.
- Add a 50-period and a 200-period SMA to a daily chart. Note the date of the most recent crossover and what price did over the next 20 candles.
- Find a period when price was ranging. Count how many times price crossed a 20-period EMA in 30 candles.
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