e50 Consistency is spelling, coherence is voice

Consistency and coherence are both important qualities in product design, and they work at different levels. Product designers need to master both.

Photo by Ian Barsby on Unsplash

☕ Consistency is spelling, coherence is voice

I was leading a team working on a fairly complex CRM product. We were building a design system, had good coverage, and once we worked through the design debt accumulated over previous eras, the screens looked great and (more importantly) consistent.

But we still saw users struggling across workflows. After some analysis, I got the designers to work together on our fundamentals. That meant going beyond design system components and screen-level consistency. In our “20% design time” we worked on understanding the business strategy, how well we served users’ goals in each flow, and what principles guided our decisions. In short, we s on consistency and started thinking about coherence.

Consistency is important in designing anything beyond the simplest software. It’s the practice of solving the same things the same way: using buttons that look the same for the same kind of action, making navigation predictable, using the same terms for the same concepts, and following brand guidelines.

Consistency is the result of systematic design. Good designers solve things consistently by following their own system, and we create design systems so that teams can be consistent across people and surfaces.

Since inconsistency is so visible, design teams often set consistency as a target in various ways, through design system compliance checks or explicit review standards. It also makes consistency-related projects, like design systems, easy to pitch to product and engineering partners, because the work shows up in the product they already care about. Consistency is also a good rationale for rebranding projects, since making software look more uniform, pages following a single logic.

This is where the tension with consistency shows up. Taken to the extreme and applied rigidly, it leads to uniformity and a stiff UX that doesn’t actually help users. Because consistency keeps the focus on internally visible problems, it can overshadow the problems real users face. Making design system compliance the target pushes designers to follow guidelines first and put usability second.

Coherence is the practice of systematic design. It goes beyond solving problems consistently. It also applies the system to which problems get solved, and considers how problems and solutions fit together as a whole. For example, destructive actions can consistently use a red delete button. If we consider the user’s intent, the button should add more or less friction depending on the consequences of the action.

Coherence connects business and user goals to design activities and gives designers an approach, a set of principles that leads to consistency in the broader system beyond the immediate screens. Applied across each layer of the design, brand, design system, journeys, and user flows, it produces consistency at every level.

To put it simply, consistency is spelling things right, while coherence is getting the grammar and the voice right. Consistency works in the touchpoints of the user journey, while coherence works across the entire journey.

Where coherence considers users’ context, builds on their existing knowledge, and serves their goals, consistency mostly serves the team’s internal goals. Those matter too, consistency speeds up development, eases maintenance, and enables better brand alignment.

Consistency makes things more predictable, timelines for the team. Coherence adds predictability also for the users. Both are essential qualities of efficient and effective design.

Naturally, coherence requires more thought and practice than consistency. Teams with weaker alignment and lower maturity tend to focus on consistency first, because it offers visible, stable guardrails that are easy to align to. As teams get better, they can make more coherent decisions. For example they can work on sharper brand articulation that enables real brand alignment, not just consistent colors and logos.

Even consistency takes effort to achieve. A good design system is key, treating it as a living system rather than a strict rulebook is what enables more coherent designs. A gammar and voice that helps designers express intent, evolving as the team’s understanding of users and business deepens.

If consistency is spelling, coherence is the grammar and voice your product speaks in. Spelling keeps you legible; voice is what makes the product actually say something.

The work for design teams isn’t only to police the rules, it’s to decide what the product is trying to say, write those principles down, and then walk a full user journey end to end asking not only “is this consistent?” but “does this sound like us, and does it help the user get where they’re going?” Coherence begins with the first flow you’ll start on this week.

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🍪 Things to snack on

Achieving and Balancing Consistency in User Interface Design by Michael Zuschlag Provides a taxonomy of inconsistency types (irregularity vs. contradiction), strength assessment, and impact analysis. Argues that contradictions are almost never acceptable, while irregularities can be justified with empirical evidence of user benefit.
“We want the best overall user experience for our users, and sometimes that means trading consistency for something else.”

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Coherent, Not Consistent by Bruno Bergher The article argues that coherence (making every part feel like it belongs) should replace consistency as the design priority. Identifies information architecture, nomenclature, and brand as the three areas where consistency remains essential, while everything else should be cleaned up periodically rather than blocking innovation.
“Coherence means making sure every part of your product feels like it belongs there, instead of trying to make them exactly the same.”

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Consistency by DOC A nuanced exploration that treats consistency as multifaceted: spanning familiarity, business efficiency, predictability, and identity. Argues that consistent principles matter more than consistent UI, and that consistency should create room for differentiation rather than suppress it. Uses the jazz metaphor: improvisation works because the foundation is consistent.
“The real power of consistency isn’t in uniformity, it’s predictability.”

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Consistency in Design is the Wrong Approach by Jared M. Spool Reframes the consistency question entirely: instead of asking “is this consistent with what we’ve designed?”, ask “will the user’s current knowledge help them use this?” Notes the irony that interfaces designed around current knowledge end up feeling consistent anyway, reinforcing the wrong lesson.
“When you think about consistency, you’re thinking about the product. When you’re thinking about current knowledge, you’re thinking about the user.”

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Design for Coherence, not Consistency by Carlos Yllobre Frames consistency-first design as artificial, rigid, and innovation-killing, while coherence-focused design is natural, flexible, and innovation-friendly. Argues that design system teams should empower product teams as contributors rather than passive consumers of locked-down components.
“When designing for coherence your focus is not just on building and maintaining the user interface elements, but on the problem you are trying to solve and the people you are trying to help.”

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Design Dialects: Enhancing User Experience by Michel Ferreira Introduces the “design dialect” concept, systematic adaptations that maintain core principles while developing context-specific patterns. Two examples, one from Shopify, how their Polaris system went from 0% to 100% task completion for warehouse pickers by creating a dialect, and another example from Atlassian and it’s Flexibility Framework: Consistent, Opinionated, Flexible tiers.
“Consistency isn’t ROI; solved problems are.”

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Design Systems: Coherence vs. Consistency by David Linke Analyzes coherence and consistency as a spectrum rather than a binary. Consistent systems (like Bootstrap) are efficient for less experienced teams, while coherent systems require more skill but produce more tailored user experiences. Concludes that organizations should be prepared for both approaches depending on context.
“A consistent design system is highly coherent, but a coherent design system does not need to be highly consistent.”