ACCESSIBLE MAPS: Color Advice for Cartography

Color coded countries on world map

Need help determining the correct color contrast for maps?

ColorBrewer to the rescue!

Created by Cynthia Brewer, Mark Harrower and other pros at The Pennsylvania State University, ColorBrewer is a diagnostic tool for evaluating the robustness of individual color schemes in maps.

Full use of the tool can benefit your map designs because colors (even very similar colors) are easy to differentiate when they appear in a nicely ordered sequence (such as a legend). The task of differentiating the colors, however, becomes much harder when the patterns on the map are complex, such as in the lower left corner of the diagnostic map.

Screenshot of ColorBrewer diagnostic color contrast tool

Here are two tests you can conduct with ColorBrewer:

TEST #1: Can you easily distinguish every color in the random section of the map (the lower left)? If you have a ten-class map, you should be able to see clearly ten unique colors.

TEST #2: Within each large band of color on the map, we placed several polygons filled with each map color (‘outliers’). For example, if you have a seven-class map, there will be six outlier colors per band, demonstrating the appearance of all map colors with each as a surrounding color. Can you see each outlier clearly? Do all pairs of outliers in the band look different? If not, perhaps you should choose a different scheme or fewer classes.

ColorBrewer also lets you determine color schemes that are colorblind-safe, print-friendly and photocopy-safe. You can also download a Microsoft Excel file with all 165 color schemes in one master file. Color schemes are also available for use on the web as CSS, JSON, and JavaScript.

Try ColorBrewer now.


WEBSITE ACCESSIBILITY TESTING & REMEDIATION SERVICES: Mary Gillen is an experienced Website Accessibility Compliance Auditor and Remediator. She can test your website to determine if it meets accessibility standards:

WCAG 2.1: 312 checkpoints covering A, AA and AAA W3 accessibility guidelines
Section 508: 15 US federal guidelines covered by 59 accessibility checkpoints

Find out more about Mary Gillen’s Accessibility Testing & Remediation Services: Websites, PDFs, Office Docs & Videos


Leave a Reply