Log vs linear price scale

Two ways to read the y-axis

Every chart has a price axis on the right side. The default everywhere is linear, which means every dollar of price gets the same amount of vertical space on the screen. So the distance between $10 and $20 on a linear chart is the same as the distance between $100 and $110. Both are ten dollars apart.

Here's the problem with that. Going from $10 to $20 is a 100% move. Going from $100 to $110 is a 10% move. On linear, they look identical, even though one is ten times more important. For a market that moves a little, that distortion doesn't matter. For a market that has grown 10x or 100x — think Bitcoin since 2015, or Tesla over the same window — linear hides the entire early history under a flat line at the bottom.

Logarithmic — usually shortened to 'log' — fixes the distortion. On a log scale, equal percent moves get equal vertical space. A move from $10 to $20 and a move from $100 to $200 take up exactly the same amount of screen, because both are 100%. The early history of a growing chart is now visible at the same scale as the recent action.

Quick default that works for most traders: linear for intraday and short-swing timeframes (1m up through daily), log for weekly and monthly. Anything where price has moved more than about three times its lowest visible value on the chart, switch to log. Anything where the visible range is tight, stay on linear — they'll look nearly identical anyway, and linear is the format most courses and screenshots use.

Recap: linear gives equal space to equal dollars; log gives equal space to equal percent moves. Default log on long-term, linear on short-term. If the answer changes when you switch, the lines were lying to you.