A scatter plot maps two variables against each other — one on the X axis, one on the Y axis — placing a dot for each data pair. It's the standard chart for exploring whether two variables are related.
How to make a scatter plot
Paste your X,Y data
Open the scatter plot maker and enter your data as two columns — X values and Y values, one pair per row. Comma-separated or tab-separated both work.
Add labels and a trendline
Set axis labels so readers know what X and Y represent. Toggle the trendline to show the linear trend across your data.
Download your chart
Save the chart as PNG or PDF.
What a scatter plot shows
Each dot represents one observation with two measurements. The pattern of dots reveals the relationship between the two variables:
| Pattern | What it means |
|---|---|
| Dots rise left to right | Positive correlation — as X increases, Y increases |
| Dots fall left to right | Negative correlation — as X increases, Y decreases |
| No pattern, random cloud | No linear correlation |
| Curved pattern | Non-linear relationship |
| Cluster with outliers | Most data is grouped, some unusual cases exist |
Understanding correlation strength
The tighter the dots cluster around an imaginary line, the stronger the correlation.
- Strong correlation — dots form a narrow band. Knowing X tells you a lot about Y.
- Weak correlation — dots are spread loosely. X and Y move together somewhat but with a lot of noise.
- No correlation — dots look like a random cloud. X tells you nothing about Y.
- Outlier — a dot far from the main cluster. Worth investigating — it may be a data error or a genuinely unusual case.
Correlation is not causation
A scatter plot shows association, not cause. Ice cream sales and drowning rates are positively correlated — both rise in summer — but ice cream doesn't cause drowning. Always ask: is there a third variable driving both?
Adding a trendline
A trendline (linear regression line) draws the best-fit straight line through the cloud of dots. It helps readers see the overall direction and estimate Y for a given X. Use it when the relationship looks roughly linear. If the dots follow a curve, a straight trendline is misleading.
When to use a scatter plot
- Exploring whether two numerical variables are related (height vs weight, study hours vs test score)
- Spotting outliers in two-dimensional space
- Visualizing the results of a regression analysis
- Comparing two measurements of the same subjects
Scatter plot vs line chart
Both plot points on an X/Y grid, but they serve different purposes:
| Scatter plot | Line chart | |
|---|---|---|
| X axis type | Any numeric value | Usually time or ordered sequence |
| Connects dots | No | Yes |
| Purpose | Show relationship between two variables | Show change over time |
| Data pairs | Independent observations | Sequential measurements |
Use a scatter plot when X is a measurement (height, temperature). Use a line chart when X is time or a sequence.
FAQ
How many data points do I need?
At least 10–15 points to see a meaningful pattern. Fewer points make it hard to judge whether the relationship is real or coincidental. More than 500 points may need transparency or binning to avoid overplotting.
What does R² mean on a trendline?
R² (R-squared) measures how well the trendline fits the data — it ranges from 0 to 1. An R² of 0.85 means the trendline explains 85% of the variation in Y. Higher is a better fit, but a high R² doesn't prove causation.
Can I make a scatter plot in Excel?
Yes — select your two columns of data, go to Insert → Charts → Scatter. For faster results with trendline and clean styling, use our free scatter plot maker.
What if my dots overlap?
Overlapping dots (overplotting) hide data density. Fix it by reducing dot size, adding transparency, or switching to a bubble chart where dot size encodes a third variable.
How this guide is reviewed
This guide is maintained by the ChartsMakers Editorial Team and reviewed for statistical accuracy, product behavior, and clarity. When a guide relies on software behavior or statistical definitions, we check it against official documentation or established references. See our editorial policy.