Every seasoned investor knows that the way you view a chart can change your entire approach to buying and selling. While most Australians start out analysing shares or property trends on a regular, or ‘arithmetic’, price scale, 2025’s market volatility is pushing more investors to embrace the logarithmic price scale. But what exactly is a logarithmic price scale, and why does it matter for your portfolio?
What Is a Logarithmic Price Scale?
A logarithmic price scale, often called a ‘log scale’, adjusts the vertical axis of a chart so that equal distances represent equal percentage changes, not equal dollar changes. For example, a move from $1 to $2 (a 100% gain) is displayed with the same vertical spacing as a move from $10 to $20 (also a 100% gain), rather than a much smaller space as in an arithmetic scale.
- Arithmetic scale: Every dollar is spaced evenly, regardless of the underlying percentage change.
- Logarithmic scale: Each increment represents the same percentage change, making it easier to visualise compounded growth.
This subtle difference can have a profound impact when analysing assets that have experienced exponential growth or sharp volatility—like tech shares, cryptocurrencies, or even Australian property prices over the past decade.
Why Log Scales Matter for Australian Investors in 2025
2025 is shaping up to be another year of significant market movement, with the ASX tech sector and alternative assets continuing to deliver double-digit swings. The log scale is especially relevant for:
- Long-term share market analysis: With the ASX200 rebounding post-2024, log scales help investors see whether recent surges are outliers or part of a sustainable trend.
- Cryptocurrency and high-growth assets: Bitcoin’s recent rally from $40,000 to over $100,000 in early 2025 is better visualised on a log chart, where parabolic moves are easier to compare to past cycles.
- Property investors: As capital city prices set new records, log scales reveal whether growth rates are accelerating or simply compounding at a steady rate.
In fact, several leading Australian brokerage platforms—including SelfWealth and CommSec—now offer log scale views as a default option for historical price charts, after investor demand surged in late 2024.
Real-World Examples: Spotting Trends and Avoiding Traps
Let’s illustrate with an example. Imagine you’re reviewing CSL Limited (ASX:CSL), which has grown from around $10 in 2000 to over $300 in 2025. On a standard arithmetic chart, the early years appear flat, with all the action clustered in the last decade. But on a log scale, you see the company’s growth has been remarkably steady—each doubling in price takes up the same vertical space, allowing for meaningful comparison across decades.
This clarity helps investors:
- Distinguish between sustainable growth and bubbles: Exponential rises that look dramatic on a linear scale may be less alarming on a log scale if they’re consistent with past growth rates.
- Set realistic expectations: If a share has already doubled several times, a log chart can temper expectations for future outperformance.
- Avoid emotional decisions: Sudden spikes or crashes may look more dramatic on an arithmetic scale, while log charts put them in historical context.
Internationally, the shift to log scales is also helping investors navigate sectors like artificial intelligence, green energy, and emerging markets—where multi-bagger returns and sharp corrections are common.
How to Use Logarithmic Scales in Your 2025 Investment Toolkit
Switching to a log scale is as simple as toggling a setting on most charting platforms. But the real power comes from integrating this view into your analysis:
- Compare assets over long timeframes: Use log charts to assess whether a share’s recent moves are out of character or part of a decades-long trend.
- Spot compounding growth: For superannuation, ETFs, or managed funds, log scales reveal whether your compounding returns are accelerating or slowing.
- Adjust technical analysis: Trendlines, moving averages, and support/resistance levels may look different on a log chart—helping you avoid false signals.
It’s also worth noting that several fintech apps now offer educational overlays, helping new investors understand the impact of log vs. arithmetic views, and guiding smarter decisions for long-term wealth building.
Conclusion
In 2025, the logarithmic price scale is more than a technical curiosity—it’s a vital tool for every Australian investor seeking clarity in a complex market. By adopting log scales, you can see through the noise, compare growth rates meaningfully, and make more confident, data-driven decisions.
