Line charts in Tableau - Step-by-Step Guide

Introduction

Line charts show how data changes over time or ordered categories. They help you see trends and patterns clearly by connecting data points with lines.

When you want to track monthly sales growth over a year.

When you need to compare temperature changes across days.

When showing stock prices movement during a trading day.

When visualizing website traffic trends by hour.

When analyzing customer sign-ups over several weeks.

Steps

Step 1: Open your Tableau workbook

- Tableau Desktop start screen or existing workbook

Your data source and worksheet are ready for use

Step 2: Drag the date or time field to the Columns shelf

- Columns shelf at the top of the worksheet

The horizontal axis shows the timeline or ordered categories

Step 3: Drag the measure you want to analyze to the Rows shelf

- Rows shelf next to Columns shelf

The vertical axis shows the values for the measure

Step 4: Click the Show Me panel and select the Line chart icon

- Show Me panel on the right side of the worksheet

Tableau draws a line chart connecting data points over time

Step 5: Drag a category field to the Color mark on the Marks card

- Marks card on the right side of the worksheet

Lines are colored by category to compare multiple groups

Step 6: Adjust axis titles and add labels if needed

- Right-click axis or use the Analytics pane

Chart is easier to understand with clear titles and labels

Before vs After

Before

Worksheet shows data fields but no visual chart, only columns and rows shelves filled

After

Worksheet displays a line chart with time on the horizontal axis and measure values connected by lines

Settings Reference

Mark Type

📍 Marks card

Choose 'Line' to create a line chart connecting data points

Default: Automatic

Date Aggregation

📍 Columns shelf date field dropdown

Control the time granularity shown on the horizontal axis

Default: Automatic (usually Year or Month)

Color

📍 Marks card

Differentiate lines by categories or keep one color

Default: Single color

Show Mark Labels

📍 Marks card Label option

Display values on data points for clarity

Default: Off

Common Mistakes

Dragging a non-date field to the Columns shelf expecting a timeline

Line charts require ordered or time-based data on the horizontal axis to show trends

Use a date or ordered numeric field on the Columns shelf for the timeline

Not selecting Line as the mark type

Tableau may default to automatic marks like circles, which do not connect points

Explicitly select Line in the Marks card to connect data points

Using too many categories on Color causing clutter

Too many colored lines make the chart hard to read

Limit categories or filter data to keep the chart clear

Summary

Line charts show trends by connecting data points over time or ordered categories.

Use date or ordered fields on the horizontal axis and measures on the vertical axis.

Select Line mark type and use color to compare categories carefully.

Practice

1. What is the primary purpose of a line chart in Tableau?

easy

A. To show trends over time or ordered data

B. To display proportions of categories

C. To compare individual values without order

D. To show relationships between two categorical variables

Solution

1. Step 1: Understand line chart usage

   Line charts are designed to show how data changes over time or ordered sequences.

2. Step 2: Compare with other chart types

   Other charts like pie or bar charts serve different purposes such as proportions or category comparisons.

3. Final Answer:

   To show trends over time or ordered data -> Option A

4. Quick Check:

   Line charts = trends over time [OK]

Hint: Line charts = trends over time or ordered data [OK]

Common Mistakes:

• Confusing line charts with pie charts
• Using line charts for categorical comparisons
• Ignoring the order or time aspect

2. Which of the following is the correct way to create a continuous line chart in Tableau?

easy

A. Drag a continuous date field to Columns and a measure to Rows

B. Drag a measure to Columns and a dimension to Size

C. Drag a dimension to Rows and a measure to Color

D. Drag a discrete date field to Columns and a measure to Rows

Solution

1. Step 1: Identify continuous date usage

   Continuous date fields create smooth, connected lines in Tableau.

2. Step 2: Understand discrete vs continuous

   Discrete dates create separate marks; continuous dates create a continuous axis for line charts.

3. Final Answer:

   Drag a continuous date field to Columns and a measure to Rows -> Option A

4. Quick Check:

   Continuous date + measure = line chart [OK]

Hint: Use continuous date fields for smooth lines [OK]

Common Mistakes:

• Using discrete dates for line charts
• Placing dimensions on Color instead of axis
• Confusing measure placement

3. Given a dataset with sales over months, what will happen if you drag Order Date (continuous) to Columns and SUM(Sales) to Rows in Tableau?

medium

A. A bar chart with sales for each month

B. A pie chart showing sales proportions

C. A scatter plot of sales vs. months

D. A smooth line chart showing sales trend over months

Solution

1. Step 1: Analyze continuous date on Columns

   Continuous dates create a continuous axis, ideal for line charts.

2. Step 2: Analyze SUM(Sales) on Rows

   SUM(Sales) aggregates sales values to plot points connected by lines.

3. Final Answer:

   A smooth line chart showing sales trend over months -> Option D

4. Quick Check:

   Continuous date + SUM(Sales) = line chart [OK]

Hint: Continuous date + measure = smooth line chart [OK]

Common Mistakes:

• Expecting bars instead of lines
• Confusing continuous with discrete dates
• Misinterpreting aggregation effect

4. You created a line chart but see disconnected points instead of a line. What is the most likely cause?

medium

A. Using a continuous date field on the Columns shelf

B. Using a discrete date field on the Columns shelf

C. Placing a measure on Color instead of Rows

D. Not aggregating the measure

Solution

1. Step 1: Identify effect of discrete date

   Discrete dates create separate marks for each date, causing disconnected points.

2. Step 2: Contrast with continuous date

   Continuous dates create a continuous axis, connecting points with lines.

3. Final Answer:

   Using a discrete date field on the Columns shelf -> Option B

4. Quick Check:

   Discrete date = disconnected points [OK]

Hint: Discrete dates cause disconnected points [OK]

Common Mistakes:

• Assuming continuous dates cause disconnected points
• Ignoring aggregation importance
• Misplacing measures on Color

5. You want to compare sales trends for multiple product categories over time in one line chart. Which approach is best in Tableau?

hard

A. Place Category on Columns, continuous Order Date on Rows, and SUM(Sales) on Label

B. Place discrete Order Date on Columns, Category on Rows, and SUM(Sales) on Size

C. Place continuous Order Date on Columns, SUM(Sales) on Rows, and Category on Color

D. Place continuous Order Date on Rows, Category on Color, and SUM(Sales) on Tooltip

Solution

1. Step 1: Use continuous date for smooth time axis

   Continuous Order Date on Columns creates a smooth timeline axis.

2. Step 2: Use SUM(Sales) on Rows for measure values

   SUM(Sales) on Rows plots sales values vertically.

3. Step 3: Use Category on Color to separate lines

   Category on Color differentiates multiple lines by color for easy comparison.

4. Final Answer:

   Place continuous Order Date on Columns, SUM(Sales) on Rows, and Category on Color -> Option C

5. Quick Check:

   Continuous date + measure + color by category = multi-line chart [OK]

Hint: Use color to separate lines by category [OK]

Common Mistakes:

• Using discrete dates causing broken lines
• Placing category on Rows instead of Color
• Not using continuous date for time axis