Reading Price Charts

What a Price Chart Actually Is

A price chart is a record of transactions plotted over time. The horizontal axis is time; the vertical axis is price. Every point or bar on the chart represents a price — or a summary of prices — from a specific moment or period. Nothing on a chart predicts the future; it only describes what already happened.

Charts appear throughout this site — on commodity pages, currency pages, crypto pages, and everywhere else. Before you interpret any of them, it helps to understand the two main formats they come in and what each one actually shows.

Line Charts vs Candlestick Charts

A line chart connects a single price point for each time period — almost always the closing price, meaning the last traded price when that period ended. It is the simplest visual possible: one dot per period, connected by a line. Line charts are easy to read at a glance, but they throw away information. If a market swung wildly during the day and then closed near where it opened, a line chart shows a flat line and hides the drama entirely.

A candlestick chart solves that problem by encoding four pieces of data for every single period instead of one. Each "candle" is a small graphic object that shows the OHLC — Open, High, Low, and Close — for that period. Learning to read one candle takes about two minutes; after that, every chart on every market starts making more sense.

Anatomy of One Candle

Imagine a single trading day. The candle for that day is built from four numbers:

• Open: the price of the first trade of the period.
• High: the highest price reached at any point during the period.
• Low: the lowest price reached at any point during the period.
• Close: the price of the last trade of the period.

The thick rectangular body of the candle spans from the open to the close. If the close was higher than the open — meaning the price rose during that period — the body is typically colored green (or left hollow). If the close was lower than the open, the body is typically red (or filled black). The thin lines extending above and below the body are called wicks (sometimes "shadows"), and they mark the high and the low for the period.

Example: suppose a barrel of crude oil opens a trading day at $80, climbs to $85, falls as low as $78, and closes at $83. The candle body runs from $80 to $83 (green, because it closed higher), the upper wick extends to $85, and the lower wick dips to $78. A line chart would show only $83.

The length of the wicks relative to the body is one of the things traders and analysts pay attention to when assessing volatility — long wicks suggest the price moved aggressively before settling. For a deeper look at volatility as a concept, see our guide What Is Volatility?

Choosing a Timeframe

Every chart covers a timeframe — the span of historical data displayed — and a period — what each bar or candle represents. These are two separate settings that are easy to confuse.

Zooming in makes every wiggle look enormous. Zooming out makes dramatic short-term moves look like barely a ripple. Neither view is "right" — they answer different questions. A chart covering one week of intraday moves tells you nothing reliable about the multi-year trend, and a 10-year monthly chart hides the detail of what happened last Tuesday. Reading charts well means being deliberate about which timeframe fits the question you're actually asking.

Percentage-change columns — day, week, month, year-to-date, year-over-year — are often more informative than the raw chart level for quick comparisons. Our guide Day, Week, YTD, YoY: Reading Percentage Moves explains exactly how those columns are calculated and what they mean.

Linear vs Logarithmic Scale

The vertical axis of a chart can use one of two scales, and the choice matters more than most people realize.

A linear scale spaces price levels evenly in absolute terms. The gap between $10 and $20 looks the same as the gap between $100 and $110 — both are $10 apart on the axis. That seems intuitive, but it creates a visual distortion on long histories: early moves look tiny even if they were massive in percentage terms, and recent moves look enormous even if they were ordinary by comparison.

A logarithmic scale (or "log scale") spaces price levels evenly in percentage terms instead. The distance from $10 to $20 (a 100% move) looks the same as the distance from $100 to $200 (also 100%). This is more honest when comparing periods at very different price levels — for example, when looking at cryptocurrency or any asset that has moved by orders of magnitude over its history.

Economists and analysts typically use log scale for anything covering more than a few years of price history, or any asset that has grown or fallen dramatically over time. On a linear chart, Bitcoin going from $1 to $100 is invisible because the line for those early years is crushed flat against the bottom axis by the scale needed to show later prices. Log scale gives every period its proportional space.

Moving Averages and Other Overlays

Most charting tools allow you to add overlays — extra lines or bands drawn directly on top of the price chart to provide additional context. The most widely discussed overlay is the moving average.

A moving average is simply the average closing price over a specified number of past periods, recalculated at every point in time. A 20-day moving average, for instance, is the average of the last 20 daily closing prices. As new data arrives, the oldest day drops off and the newest day is added — hence "moving." The result is a smoother line that filters out short-term noise and makes the underlying direction of price easier to see.

Common moving average lengths people reference include 20-day, 50-day, and 200-day periods for daily charts. On longer timeframes, weekly or monthly averages are often used instead. A simple moving average weights every period equally. An exponential moving average gives more weight to recent periods, so it reacts faster to fresh price changes.

It is important to understand what a moving average is and is not: it is a mathematical description of past prices, calculated and displayed after the fact. It does not predict where the price is going. Analysts use moving averages to describe context — "the price has been running above its 200-day average" is a factual statement about the past, not a statement about the future. For more on how market data like this is quoted and described, see How Market Quotes Work.

Sparklines: A Year at a Glance

Across this site you will see small inline charts called sparklines — tiny, stripped-down line charts that appear next to a price or percentage figure in a table. A sparkline typically compresses around 52 weeks of weekly closing prices into a thumbnail roughly the size of a word. There are no axis labels, no grid lines, and no numbers on them. Their only job is to give your eye an instant sense of direction and shape over the past year.

A sparkline rising steeply from left to right tells you the price has trended up over the period. A flat sparkline with a big dip in the middle tells you the price fell and recovered. A jagged, irregular sparkline suggests a volatile, choppy year. None of this is precise — it is a visual shortcut, not a data point. For precise figures, the percentage-change columns next to the sparkline carry the actual numbers.

Understanding what sparklines compress — and what they leave out — helps you use them correctly: as a quick directional summary, nothing more.

Putting It All Together

Reading a price chart well comes down to a short checklist: What asset is this? What does each candle represent (one day? one week? one month?)? Is the scale linear or logarithmic? What does the overlay describe, and what data went into it? Answering those four questions before drawing any conclusions prevents the most common misreadings.

Charts are a language. Like any language, the goal is not to mistake the description for the thing being described. A chart of oil prices is not oil; a moving average on a gold chart is not a prediction about gold. It is a record of what buyers and sellers agreed to pay, organized visually so that patterns over time become easier to see. For context on what is actually being agreed to when a price is set — including spot prices, futures prices, and settlement conventions — our guides on Spot vs Futures Prices and What Is a Futures Contract? are a natural next step.