How to use charts

A chart is a visual display of information.

The main purpose of a chart is to help people understand and compare. Our charts should be:

  • Useful. To help people understand a chart, we pair data with interpretation.
  • Trustworthy. Include clear copy, including accurate labels, units, and timeframe.
  • Based on behavioral science. Use charts to nudge people to change their behavior.

Creating a chart

Get your story straight, then choose the right format.

  1. Articulate the concept

    Before you start making a chart, figure out what you want to communicate. The same data can have different interpretations, so it’s up to you to decide what story to tell.

  2. Choose the right format

    Keep in mind that not every piece of data needs to be displayed in a chart—often, a simple table or other visual comparison will do.

  3. Add insight or interpretation

    Call out an interesting aspect of the data in a short sentence like so: Heating accounts for 36% of your energy use.

  4. Double-check the details

    Include in all chart types:

    • Heading (descriptive, use sentence case)
    • Labels
    • Units of measurement
    • Reference to time
    • Insight or interpretation

    Depending on the content, charts can also have:

    • Key
    • Caption
    • Tooltips
    • Related body copy

What type of chart to use

Bar and column chartLine chart and area chartPie chart
Best for…Comparing using same characteristic
Discrete amounts
Changes over time
Continuous series
Part-to-whole relationship
Emphasis on…Relative size of barsRelationship between points
Peaks and valleys
Relative size of slices
ProsEasy to compareShows lots of data at once
Visual interest
Visual interest
ConsCan be hard to compare slices