Volatility explained: what it is, how to measure it, why it matters

Volatility is how much and how fast a price moves. It says nothing about direction: a market that rises 40 pips and one that falls 40 pips in the same time are equally volatile. For short-expiry trades, volatility is the quantity that decides whether your expiry is long enough for an idea to play out — and how easily random wiggles can flip the result.

Volatility is about size, not direction

Think of two quiet afternoons. On the first, EUR/USD drifts between 1.0850 and 1.0858 for an hour. On the second, it swings between 1.0820 and 1.0890 and ends the hour exactly where it started. Neither hour had a trend, but the second was far more volatile. A 1-minute trade during the first hour depends on a pip or two; during the second, the same minute can move ten pips either way.

The intuition behind standard deviation

The textbook measure of volatility is the standard deviation of price changes. You don't need to calculate it by hand, but the idea is worth having:

1. Take a series of price changes — say, the change from one M1 close to the next over the last 20 minutes.
2. Find their average.
3. Measure how far each change typically sits from that average.

If most minutes change by roughly 1–2 pips, the standard deviation is small. If some minutes move 1 pip and others 8, it is large. Under a common simplifying assumption, about two thirds of changes fall within one standard deviation of the average and about 95% within two. Real markets have more extreme moves than that idealised picture, which is one reason surprises happen more often than the maths suggests.

A useful consequence: in a random-walk-like market, typical movement grows roughly with the square root of time, not in proportion to it. If price typically moves about 2 pips in one minute, it tends to move about 4 pips in four minutes, not 8. That is a rule of thumb, not a law, but it explains why doubling your expiry does not double the room your trade has to work.

Volatility clustering

Volatility tends to come in clusters: calm periods follow calm periods, and wild periods follow wild ones. A burst of large candles after a data release is usually followed by more large candles for a while, then a gradual return to quieter conditions. On real markets, clustering is linked to trading sessions (activity rises when London and New York open; see forex market sessions) and to news on the economic calendar.

Clustering is one of the few properties of price that is fairly dependable: knowing the market is volatile now tells you something about the next few minutes. Not the direction — the size.

On OTC instruments, Sky Trade's price is generated by its own server with a random-walk model whose volatility changes slowly over time. OTC prices do not track any real market, so session opens and news have no effect on them; their quiet and busy phases come from the model itself.

How to measure volatility on a chart

• ATR (Average True Range). The average size of recent candles, including gaps between them. If ATR on M1 reads 3 pips, an average minute recently covered about 3 pips from high to low. It is the most direct answer to "how big are moves right now?" — see the ATR guide.
• Bollinger Band width. The distance between the upper and lower Bollinger Bands is based on standard deviation. Bands that pinch together (a squeeze) show low volatility; bands that flare apart show expansion.
• Raw candle ranges. Simply comparing the last few candles to the previous twenty is surprisingly effective. If recent candles are twice as tall as usual, conditions have changed.
• Instrument pages. Each instrument page on Sky Trade, for example EUR/USD, shows volatility computed from Sky Trade's own price feed, which is handy for comparing instruments before you open the terminal.

A worked example

Suppose ATR(14) on GBP/USD M1 reads 2.5 pips. You see a setup you believe could carry price 4 pips higher.

• With a 30-second expiry, typical movement is around 2.5 × √0.5 ≈ 1.8 pips. Your expected 4-pip move is unlikely to finish in time, and noise of a couple of pips can easily decide the trade.
• With a 3-minute expiry, typical movement is around 2.5 × √3 ≈ 4.3 pips. Your idea now has roughly the room it needs — but so does the noise, which is equally capable of moving against you.

The arithmetic is only illustrative; it does not make either trade a good one. What it shows is the relationship: an expiry that is too short relative to volatility leaves your analysis no time to matter, while a longer one gives both your idea and randomness room to work. For a full discussion, see choosing expiry time.

Why volatility matters for short expiries

• Low volatility + short expiry — the trade is often decided by a pip or less, so ties and near-ties are common, and small ticks dominate.
• High volatility + short expiry — large random swings can carry price far in either direction within seconds; a correct idea can lose to a single spike.
• Sudden expansion — after a quiet phase, the first big candles of an expansion are where false breakouts and sharp reversals cluster.

Typical mistakes

• Treating high volatility as opportunity by default. It enlarges moves in both directions.
• Increasing the stake when the market "is moving". Larger swings mean larger uncertainty, not better odds.
• Using the same expiry in a dead Asian-session hour and right after a major data release.
• Confusing volatility with trend. A wildly swinging range has high volatility and no trend.

How to set it up in the Sky Trade terminal

Add ATR or Bollinger Bands from the indicators list above the chart; ATR appears in a separate panel below the price, Bollinger Bands on the price itself. Keltner and Donchian channels in the same list also widen and narrow with volatility.