--- title: "Log Price: Formula, Meaning & Signals" description: "Log price is the natural logarithm of the price. On a log scale equal vertical distances represent equal percentage changes, and the difference between two..." canonical: https://www.getswoopr.com/indicators/price-and-structure/log-price/ source: "Swoopr Investment: https://www.getswoopr.com" --- ## Direct Answer > Log price is the natural logarithm of the price. On a log scale equal vertical distances represent equal percentage changes, and the difference between two log prices is the continuously compounded return. A steady straight line on a log chart means a constant percentage growth rate. # Log Price: Formula, Meaning, Signals, Examples and How to Use It ## How Is Log Price Calculated? Log price is the natural logarithm of the price. On a log scale equal vertical distances represent equal percentage changes, and the difference between two log prices is the continuously compounded return. **Formula:** `Log price = ln(P); log return = ln(P_t) - ln(P_t-1)` **Inputs:** - Price series (positive values) **Worked example.** A price rising from 100 to 110 has a log return of 0.0953, close to but below the 10% simple return. The inputs are illustrative numbers, not market data. **Reading it.** A steady straight line on a log chart means a constant percentage growth rate. Log scaling makes moves of different price levels comparable, which matters for long histories or large price changes. **Limits.** It requires strictly positive prices. Log returns add across time but do not add across assets in a portfolio, and for small moves they differ little from simple returns. ## What is Log Price? Log price is the natural logarithm of the price. On a log scale equal vertical distances represent equal percentage changes, and the difference between two log prices is the continuously compounded return. ## How to use Log Price A steady straight line on a log chart means a constant percentage growth rate. Log scaling makes moves of different price levels comparable, which matters for long histories or large price changes. A reading alone is never a buy or sell signal; it needs context from price structure, volume, volatility and the broader market regime. ## Strengths - Equal vertical steps correspond to equal proportional changes, so a move from 10 to 20 and one from 100 to 200 look the same on a log scale. - Differences of log prices add across consecutive periods, so a multi-period return is just a sum of single-period values. - Reproducible when the formula and data convention are fixed. ## Weaknesses and limitations - Log values are unitless numbers of little direct meaning and must be exponentiated to be read back as price levels or percentage changes. - On a log chart, large dollar swings at high price levels look visually compressed, which can make a major move appear modest. - Correlated indicators can create false confidence by repeating the same underlying information. ## Editorial and risk note This page is educational content, not individualized investment advice. It should not imply guaranteed prediction, accuracy or outperformance. ## Frequently Asked Questions Is Log Price a buy or sell signal? No. A steady straight line on a log chart means a constant percentage growth rate. It requires strictly positive prices. A trade built on it still needs a trigger, an invalidation rule, a position size and realistic execution assumptions. What is the best setting for Log Price? Log Price is computed from price series (positive values), so the choices that matter are the data convention and the window it is read over. Test those across instruments, regimes and out-of-sample periods instead of fitting one historical winner. Can Log Price be used by itself? It requires strictly positive prices. Log returns add across time but do not add across assets in a portfolio, and for small moves they differ little from simple returns. For that reason it is read next to measures of direction, participation, valuation, liquidity and risk, not alone. Does Log Price work on every timeframe? The calculation (Log price = ln(P); log return = ln(P_t) - ln(P_t-1)) can be run on any bar size, but behavior is not portable: a reading on a five-minute chart describes a very different market window from the same reading on a daily chart. Validate the exact timeframe before relying on it. Why does Log Price give false signals? Log values are unitless numbers of little direct meaning and must be exponentiated to be read back as price levels or percentage changes. On a log chart, large dollar swings at high price levels look visually compressed, which can make a major move appear modest. Lag, noise and regime changes add to this, because market participants react to new information after the reading is calculated. How should Log Price be backtested? Rebuild Log Price from price series (positive values) using point-in-time data, write the rules before testing, include delisted securities where relevant, model realistic fills and costs, reserve a validation sample and compare with a simpler baseline. S Swoopr Editorial Team The Swoopr Editorial Team produces independent investment education, research, and tools for understanding markets, evaluating opportunities, and managing risk. All content is educational only and does not constitute personalized investment advice. See our [editorial policy](https://www.getswoopr.com/legal/editorial-policy/) and [corrections policy](https://www.getswoopr.com/legal/corrections-policy/).