Axes and labels

Axes and labels provide critical context for the information within a chart. Use simple, easy-to-understand descriptors and metrics to label your chart and axes.

Starting at zero

Always start numerical axes at zero for part-to-whole and comparisons charts. For bar and area charts, a truncated Y-axis can distort the perceived scale of a chart, making a small difference appear more significant than it is.

Legends bahvior highlight on hover

For bar charts, the numerical axis should start at zero.

Legends bahvior highlight on hover

When an axis starts at non-zero, percentage differences between bars are exaggerated.

It’s acceptable to start line charts and scatter plots at a value higher than zero. These types of visualizations are less sensitive to distortion because they communicate trends rather than difference in size or quantity. In these cases, cropping the Y-axis helps users better identify the direction of change.

Gap in data denoted by texture

For line charts showing stock market activities, the existence of peaks and valleys in trends is more important than the true size of the change.

Gaps in data

Use the designated texture to denote the range or period when data is not available. Always label both start and end points where data is not available.

Gap in data denoted by texture

Breaks in axes

Sometimes it’s useful to skip part of the axis to bring data on the extreme ends into view without distortion. When axes contain a break, use a sinusoidal line to replace the straight axis line.

On the X-axis, the break may be fluid with graph area size, with a minimum width of 16px. On the Y-axis, we recommend fixing the distance break at 16px.

Gap in data bar chart

If data is available during an axis break, restyle line segments to use 0.5px stroke and hide circles representing data points.

Gap in data denoted by texture

If data isn’t available between break points, denote the data gap with a texture.

Gap in data denoted by texture

Time series

Consistent increments

If any form of axis compression is required, use the provided axis break styling to visually denote the compression.

Localization

In time series, X-axis labels reflect the time increment in the data. When possible, use localized date and time format, or user preference. Otherwise, the chart defaults to the format presented below.

Landmark labels

Whenever data cross into a new time cycle, such as a new day, month, or year, semibold the label to emphasize the transition.

Gap in data denoted by texture

Example of a time series plotted at 15 seconds intervals