It’s no secret that the smart use of color in visual plan communications is a great way to engage your audience, distinguish important elements and evoke the proper reaction.

In Western cultures, for instance, “red” typically connotes “bad” or “risky.” It’s a great way to get the message across that a particular deliverable is in trouble without cluttering your chart with extra words.

But there’s a problem with only using color to deliver critical information in a project graphic. According to the National Eye Institute, as many as 8 percent of men and 0.5 percent of women with Northern European ancestry are color-blind. They have trouble distinguishing – or in some cases can’t distinguish at all – between red and green (more common) or blue and yellow (less common). Green means go and red means stop, but for those with red-green color-blindness, neither means much of anything.

How last year’s Bills (red) vs. Jets (green) “Color Rush” NFL game looked to color blind individuals. h/t The Sporting News

How can you ensure your plan communications are accessible and useful to all? Here are three tips.

1. Use Color Judiciously

This isn’t to say you should simply not use color in your graphics. Doing so would mean removing a remarkably valuable and effective arrow from your quiver. Instead, use it smartly and sparingly. The rule of thumb is this: If viewers need to repeatedly refer to a legend to understand what certain colors mean, you’re using too many. Six is a good maximum, with the ideal being around three or four. This is a good idea in general, but applies particularly acutely to the color-blind population. They’re going to be paying far closer attention to color than most, and its overuse will likely distract them, rather than engage them.

Using too many colors makes a chart extremely hard to understand, color-blind or not.

2. Avoid Shades

Once you’re beyond six colors in a chart, you’re almost certainly using multiple shades of similar colors. To a color-blind individual, it’s likely that purple, dark purple, blue, and dark blue are going to be indistinguishable from one another. By limiting the number of colors you use, you force yourself to avoid such close shades. The more differentiation, the better.

On a similar note, try to avoid using only red and green or blue and yellow. These combinations are particularly troublesome to color-blind individuals, who will have trouble telling one or both sets apart.

3. Add Elements

Color isn’t the only way to delineate elements in a plan communication graphic. Shapes – rectangles, circles, stars and chevrons – can be just as evocative. When color is the only way, consider judiciously using hash marks or different borders as additional visual cues.

In this example, status is shown using both color and shape.

By keeping these tips in mind, you can ensure that your valuable data is accessible to all, color-blind and not.