How to Make a Line Graph: A Step-by-Step Guide
Learn when to use a line graph, how to set up data over time and make one in minutes, plus tips for clear, honest line charts, with a free line graph maker.
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Free tool: Line Graph MakerA line graph connects data points with a line, so the eye follows the ups and downs from left to right. It's the natural choice for anything that changes over time: sales by month, website visitors by week, temperatures by day. This guide explains when a line graph works best, how to set up your data and how to make one with the free Line Graph Maker.
When to use a line graph
Line graphs are best for:
- Trends over time, such as monthly revenue, daily step counts or yearly population.
- Spotting patterns: growth, decline, seasonal peaks and sudden changes.
- Continuous measurements taken at regular intervals, such as hourly temperatures.
Use a different chart when the categories aren't connected in a sequence. Sales by region or votes by candidate belong in a bar graph, because a line between unrelated categories suggests a trend that isn't there. For more on the choice, see Bar Chart vs. Line Chart.
Step 1: Set up your data
You need a label for each point in time and a value for each label, in order. For example, an online shop's monthly sales in thousands of dollars:
| Month | Sales ($ thousands) |
|---|---|
| Jan | 12 |
| Feb | 15 |
| Mar | 14 |
| Apr | 18 |
| May | 21 |
| Jun | 24 |
Keep the time steps regular, all months or all weeks. The graph spaces the labels evenly, so a missing month would make the line jump without showing the gap.
Step 2: Make the line graph with Graph Maker
- Open the Line Graph Maker. It works in your browser, with no account needed.
- Type a chart title, such as "Monthly Sales, January to June".
- Enter your data. With Input Format set to Title & Value Together, type each label and value as a pair:
Jan:12,Feb:15,Mar:14,Apr:18,May:21,Jun:24. Or choose Title & Value Separate and type the labels (Jan,Feb,Mar,Apr,May,Jun) and the values (12,15,14,18,21,24) in their own boxes. Type numbers without thousands separators, because commas separate the entries. - Add the axis titles: the horizontal axis ("Month") and the vertical axis, including units ("Sales ($ thousands)").
- Choose the line type. Straight Line joins the points with straight segments; Curve Line draws a smooth line through them.
- Pick the colors of the line, the background, the title and the text.
- Download the graph as a PNG for documents and slides, an SVG that stays sharp at any size, or a JPG.
Hover over any point to see its exact value.
Straight or curved?
Straight lines are the honest default: each segment simply connects two measurements. A smooth curve looks friendlier and suits data that really changes smoothly, such as temperature through the day, but it can suggest values between the points that were never measured. If every point is a separate measurement, such as monthly sales, straight lines are usually the better choice.
Tips for a clear line graph
- Put time on the horizontal axis, running from left to right.
- Label the units. "Sales ($ thousands)" tells readers what a value of 24 means.
- Show enough points to see a trend. Two or three points rarely make a pattern; a dozen usually do.
- Mark the points that matter in your text, such as the peak month or a sudden drop, so readers know where to look.
- Avoid reading too much into small wiggles. Month-to-month noise is normal; look at the overall direction.
- Start the vertical axis at zero when the size of the values matters. The maker starts at zero, which keeps changes in proportion.
- Compare series carefully. This maker draws one line; to compare two groups side by side, a grouped bar graph works well, and an area chart emphasizes the size of a total over time.
Frequently asked questions
What is a line graph used for?
Showing how something changes over time, such as sales, prices, temperatures or website traffic. The line makes rises, falls and patterns easy to see.
What's the difference between a line graph and a bar graph?
A line graph connects points in a sequence, so it suits time series and trends. A bar graph compares separate categories, such as regions or products, where connecting the values with a line wouldn't make sense.
Should a line graph start at zero?
Not always. Because readers look at the shape of the line rather than the length of bars, a line graph can zoom in on a narrow range to show small changes, as long as the axis is clearly labeled. Starting at zero is safer when you want the size of the changes to look proportional.