When I create architecture diagrams or slide decks, I often rely on color coding to highlight recurring concepts or distinct domains. It helps the audience recognize patterns quickly without having to re-read every label.
However, finding the right palette is surprisingly difficult. The colors need to be distinct enough that everyone can tell them apart easily—even on a bad projector or for people with color vision deficiencies—but they also need to be pleasant to look at. A random selection often ends up looking messy or lacking sufficient contrast.
Over time, I have settled on two reliable resources that solve this specific problem.
The classic approach: Kelly colors
My primary reference for a long time has been the Kelly colors. These are a set of 22 colors chosen to have maximum contrast with one another. They were originally proposed by Kenneth L. Kelly in the mid-20th century, specifically for use in charts and graphs where distinctness is paramount.
The sequence is designed so that the colors are distinct not just from white and black, but also from every preceding color in the list. This makes them incredibly useful for technical diagrams where clarity wins over aesthetics.
I usually refer to this list:
A modern alternative: Sasha’s 20 colors
While Kelly colors are functional, they can sometimes feel a bit harsh depending on the context. Recently, I have started using a set of “20 simple, distinct colors” compiled by Sasha Trubetskoy.
This set aims to achieve the same goal—maximum distinctness—but with a slightly more modern feel. The author put significant effort into ensuring accessibility (99% accessible for colorblind users) and differentiating between similar hues like red and pink.
For presentations where I want things to look a bit more polished while keeping the information readable, this is a great alternative:
What about online generators?
There are excellent tools available for generating custom color palettes, such as Coolors or Adobe Color. These are fantastic if you need to match specific brand guidelines or want to explore color theory.
However, for diagrams or standard presentations where clarity is the main goal, I find them to be overkill. It is significantly easier and safer to rely on a proven, accessible list like the ones mentioned above. It saves decision-making time and guarantees that the colors will be distinct enough for everyone to see, without the hassle of manual tweaking.