Bar Chart

A bar chart displays data using rectangular bars, where the length of each bar represents the value associated with a category. Categories are placed along one axis (typically the horizontal axis), and values along the other.
This chart type is ideal for comparing magnitudes across distinct, discrete categories and for highlighting differences at a glance.

When to use it

Compare quantities across distinct categories (e.g., sales by product, revenue by region).

Highlight differences between groups in a clear and straightforward way.

Display rankings (e.g., top-performing departments or products).

Use when categories represent distinct items, not a continuous progression.

Best suited for a limited number of categories to maintain readability.

When NOT to use

For continuous data over time → use a lines chart instead.

When there are too many categories (>10–15).

When precise trend analysis is needed.

Data requirements

1 categorical dimension (e.g., product, region)

1 numeric measure

Optional: grouping for sub-categories

Use cases

Metering Data Monitoring Service (MPO) – 50Hertz EPIC Portal

This stacked bar chart shows the daily status of meter data transmissions for all MaLo.
Each bar gives a quick view of what was sent on time, sent late but complete, or missing and overdue.
By clicking on a bar, you can see the detailed list of MaLo for that day, with filters by status.
This helps easily identify problematic MaLo and export the list for follow-up.

Accessibility

Ensure high color contrast (WCAG compliant) for all elements.

Use patterns or direct labels in addition to color.

Provide alt text and include a data table as an alternative view.

Use clear axis labels and display values directly on bars when relevant.

Limit the number of categories to maintain readability.

Don't

Rely solely on color to differentiate categories.

Omit alternative indicators (labels, patterns).

Remove axis labels or units.

Use very similar colors across categories.

Overload charts with too many categories.

Column Chart
Vertical version of a bar chart; often used interchangeably depending on layout or readability constraints.

Stacked Bar Chart
Shows the composition of each category by stacking segments within a single bar.

Bar Chart
Displays multiple series side by side for each category, enabling comparison between sub-groups.

Histogram
Similar in appearance, but used for continuous data grouped into intervals (bins), not categorical comparison.

Dot Plot
Uses dots instead of bars, offering a cleaner and more compact alternative, especially for many categories.

Bullet Chart
A compact variation that includes targets or benchmarks alongside actual values.

Lollipop Chart
A lighter alternative where bars are replaced with lines ending in a dot, improving visual readability in dense datasets.