5 Tips for Writing Good Design Principles

Strong design principles will help you make better design decisions about products and features

Ethan Eismann


Illustration: Jennifer Hom

EEvery product or feature should be based on a set of design principles. I’m not talking about universal design principles like “less is more” or “simple.” Instead, I’m talking about design principles that uniquely apply to the specific product or feature that you’re building.

Think of it this way: Universal design principles apply to everything. They’re like air or gravity or other things inevitable and necessary. Just learn then, apply them, and move on. On the other hand, the kind of design principles this article focuses on are those specific to the product or feature you are designing now. Which is different from the other product or feature you designed last month. For example, at Slack we expect the principles that guide design from the Messaging team to be different from principles that guide design from the Search team.

Now, a word on why principles are important. Fundamentally, design principles are important because they help your team make decisions. Design principles should be foundational; set them up first, before you start designing. Then, as you move through the design process, refer back to the principles. Question whether your design decisions uphold the principles or break them. For example, in a recent project related to the redesign of Slack’s information architecture, we established a principle to provide the lowest number of access points possible to meet the user’s primary intent. By sticking with this principle we were presented with the hard work of identifying why people primarily use Slack (with such an open-ended product, there is no shortage of opinions about that) and made hard decisions to eliminate a number of top-level UI elements. But the principle served its purpose. It helped us make decisions, efficiently, and move forward.

One last note before we get to the tips: Design principles are meant to be reflexive. Through the design process you may find that, based on your design and what you learn about it, the original principles may need to be adjusted. Perhaps you receive overwhelmingly positive user feedback on a design that is in conflict with a principle. That’s an indication the principle should be a candidate for reconsideration. While good design principles (that follow the tips below) typically won’t be significantly adjusted during the design process, principles aren’t meant to be immutable. They should be treated as a living part of the design process.

So, now to the good stuff: How to write effective product- or feature-specific design principles?

1. Make them opinionated

The purpose of design principles is to help your team make decisions. Accordingly, effective principles offer a point of view. This POV should be based on the needs of your users, their current perception of your product, and your business context. For example, one of the design principles Slack’s Admin design team uses is “prioritize flexibility over simplicity.” This principle is informed by the POV that Slack is used in a wide range of industries, regions, and scales, and therefore Slack administrators are extremely different from each other. In order for them to be most confident in their role, admins need to be able to customize the tool to fit their unique context. What I love about this principle is that it’s informed by what we know about our admin users, and it also has a POV. It states that the team will do X over Y. The opinionated nature of this principle makes the team’s decision-making much easier.

2. Make them unambiguous

Good design principles should be clear and exacting and have no double meaning. Think about the context you are designing for. Is it for a medical use case, photo sharing, a meditation app? Use your context as a guide to refine the wording of your principles so they clearly convey a singular meaning to people on your team. One helpful technique is to make your users a part of your principles. For example, when designing a photo- or video-sharing app you might want to include the term “creator” in a principle. Something like: “We always give creators control over their content.” This is much clearer than “Give control over content.”

3. Make them memorable

Use one simple, pithy sentence to express each principle. Two sentences is one too many. Don’t use complicated or sophisticated words. That said, it’s entirely okay to couple your one-sentence principle with complementary text. However, that complementary text shouldn’t be required to make sense of the principle. Also, the fewer principles the better; too many principles dilute their decision-making ability. I’ve found three principles to be an effective number for a product or feature. It’s easy to remember three sentences, and it’s a large enough number to pertain to most types of decisions.

4. Make them relevant

As much as possible, pair each principle with a common example. Showcasing how the principle was used to make a decision in the past will help your team better understand how to apply the principle to future decisions. The best examples are sourced from within your own company. These tend to be most relevant because your team has firsthand experience with the example.

5. Use them regularly

Good principles are put into use. Print them out. Put them up in your design space. Refer to them during critiques. It may feel uncomfortable or artificial at first, but over time your team will grow accustomed to using the principles to make better decisions.

Good luck forming your own design principles, and happy decision-making!



Ethan Eismann
Writer for

Design and product leader. Father of two. Amateur ceramicist and beekeeper. VP of Design at Slack. @eeismann / ethaneismann.com