Log vs linear chart: why the same chart can look so different
Open a 20-year stock chart on a linear scale and the early years look flat. Switch to log scale and they suddenly come alive. The price didn't change. The ruler did.
The short answer
On a linear scale, every dollar takes the same space. A move from $10 to $20 looks the same height as $100 to $110.
On a log (logarithmic) scale, every percent takes the same space. A move from $10 to $20 (+100%) looks the same height as $100 to $200 (+100%).
For short-term charts, the two look almost the same. Over years, or after huge moves, they look very different.
Side by side
| Linear scale | Log scale | |
|---|---|---|
| Equal spacing means | Equal dollars | Equal percent |
| $10 → $20 vs $100 → $110 | Same height | $10 → $20 looks ~7× taller |
| Long-term charts | Early years look flat | Early moves are easy to see |
| Short-term charts | Fine | Looks nearly the same |
| Trendlines over years | Often curve away | Often fit better |
| Common for | Day trading, small ranges | Long histories, crypto, big growers |
Linear, in plain words
The price axis is a normal ruler. $1 is $1, wherever it is on the chart.
The good parts:
- Simple. What you see is the dollar move.
- Fine for short charts. On a 5-minute chart of a day's trading, price barely changes in percent, so scale doesn't matter much.
- Matches dollar stops. A $2 stop looks like a $2 stop anywhere.
The limits:
- Hides early history. If a stock went from $5 to $500, the move from $5 to $50 (a 10× move) looks like a flat line.
- Recent moves look huge. A 10% drop at $500 looks much bigger than a 50% drop at $20.
Log, in plain words
The axis is spaced by percent. Each doubling takes the same height.
The good parts:
- Fair comparison. A 20% move looks like a 20% move, at any price.
- Long histories make sense. You can see what really happened in the early years.
- Trendlines. On long charts of fast-growing assets, lines drawn on log scale often fit better. See how to draw trendlines.
The limits:
- Dollar moves look squashed at high prices.
- Lines differ by scale. A trendline drawn on log may cross at a different price than on linear. Know which one you used.
A quick example
A stock rises from $10 to $20, then from $20 to $30.
- In dollars: both moves are $10.
- In percent: the first is +100%, the second is +50%.
On linear, the two moves look the same size. On log, the first looks about 1.7 times as tall as the second. A math example of how scales work, nothing more.
Where to switch it. On TradingView, look for a small "log" option at the bottom right of the price axis, or right-click the price scale. See how to use TradingView.
Which fits you?
- Day trading or short swings? Linear is fine. Over a day or a week, the two scales barely differ.
- Looking at years of history? Log shows the real shape of the move.
- Crypto or stocks that moved 10× or more? Log is usually clearer. See crypto vs stocks.
- Drawing long trendlines? Pick one scale and stick to it for that chart.
Levels where price turned around are prices. They're the same on both scales. Only the spacing between them changes. See support and resistance.
Common mistakes
- Judging an old move on a linear chart. A 10× gain can look like nothing.
- Drawing a trendline on one scale, checking it on the other. It won't line up.
- Thinking the scale changes the trade. Your entry, stop and size are still prices and dollars. The position size calculator doesn't care about scale.
- Calling a big recent drop "the worst ever" from a linear chart. Check it in percent first.
Questions
Should I use log or linear scale?
For short-term charts, either is fine. For long histories or assets that moved many times their price, log scale gives a fairer picture because equal space means equal percent.
Why do long-term charts look different on log scale?
Log scale spaces prices by percent. Early moves at low prices, which look flat on linear, show their true size in percent.
Do support and resistance levels change on a log chart?
The price levels stay the same. The spacing between them changes, which can make some look closer or further apart.
Is log scale better for crypto?
Many traders use it for long crypto charts because prices have moved so far. For short timeframes, the difference is small.
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