Thanks to Jeremy Elliott and our friends at Noun Project for contributing this post!

When designing an icon set, one of the most important things to keep in mind is that a set is more than just a collection of individual icons—it’s a cohesive visual story. Great icon sets can flesh out a detailed picture of a particular subject or topic with consistency, clarity, and intentionality. Whether you’re illustrating a broad theme or specific objects, maintaining a unified style across your icons is essential for helping your icon set look polished, professional, and well informed.

So, what exactly makes a great icon set? Let’s explore the key elements:

Start with Subject Matter

A great icon set starts with a strong concept. Before diving into the design process, spend some time thinking about the subject matter. Ask yourself: What message is this set trying to convey? What will the icons be used for? This initial clarity will guide the entire design process. If you’re designing a set around a specific theme, like “tools” or “outdoor activities,” ensure that every icon clearly relates to the theme. Avoid including icons that feel out of place, even if they’re visually appealing.

And don’t forget these two key considerations before you start designing:

Subject matter specificity: A lot of icon sets already exist in the world – how are yours going to stand out? It’s easy to find icons for general topics like web navigation (including home buttons, “settings” gears, and so forth) so what less-represented topics can you create icons for?

Diversity and inclusion: It’s important to represent a wide and diverse range of people in your work, and to avoid outdated stereotypes. Depictions of people should include a variety of different ages, hair types and styles, body types, facial features, and identities.

At left, Olena Panasovska’s “Fungi” icon set, and at right, Azam Ishaq’s “Free Time” icon set, each has a unifying topic as well as a distinct visual style and presentation that repeats through every icon.

Next, Decide on a Style

One of the decisions you’ll need to make when creating an icon set is defining its visual style. Are you going for a minimalist approach with simple lines, or do you want to experiment with more detailed illustrations? The style you choose should not only reflect your personal design aesthetic but also cater to the end user and the types of visual collateral that might be created using your icons. For example, a minimalist, flat design may be ideal for app icons or user interfaces, while a more playful, hand-drawn illustrative style could suit an educational project or a children’s book.

Whatever direction you take, it’s crucial to remain consistent with your design elements throughout the set. This means using the same line thickness, level of detail, and overall proportions across all icons. A cohesive style ensures your icons will work seamlessly together, rather than feeling disjointed.

Even using just one color, the aesthetic style choices you can make are seemingly limitless. Making a decision between abstract and literal, curvy or straight, filled or outlined, illustrative or symbolic, detailed or simple, will guide the entire set you create.

Consistency is Key

For an icon set to feel unified, the icons must share the same visual language. This includes consistency in fill or stroke weight, corner radii, and any additional design flourishes like shadows or patterns. A common mistake is allowing small variations between icons. Even minor inconsistencies in stroke weight can disrupt the harmony of the set, causing the icons to look out of place when used together.

If you’re using a stroke-based design, ensure that all your icons have the same stroke width throughout. Similarly, if your icons use filled shapes, the balance of positive and negative space should be even across the set.

In Vanicon Studio’s “Mammals” icon set, an identical style is applied to every animal, with the same outline form, stroke weight, balance of curves and straight lines, and simplistic face with a small dot for an eye.

Visual Hierarchy and Simplicity

Icons are meant to convey information quickly and clearly. To achieve this, you’ll want to design with simplicity in mind. This doesn’t necessarily mean your icons have to be basic or void of detail, but they should prioritize clarity over complexity. Each icon should have a clear focal point, with any secondary elements playing a supporting role. This visual hierarchy ensures that users can instantly identify what the icon represents. Keep the design as straightforward as possible while still being visually engaging.

Testing for Scalability

Scalability is another important factor in a great icon set. Icons are often used in a wide variety of sizes, from tiny favicon applications to large prints on posters or billboards. It’s essential to ensure your icons maintain clarity and balance at all scales. A good way to test this is by previewing your icons at different sizes as you design. Icons that look great at 256×256 pixels might lose their impact when scaled down to 16×16. Ensuring that your designs remain legible at small sizes will make them more versatile and user-friendly.

The Power of Unity

Ultimately, a great icon set is one where all the icons feel like they belong together. This sense of unity is what makes an icon set powerful. When users can mix and match icons from your set without breaking visual cohesion, it makes their experience seamless and enjoyable. To achieve this, always keep the broader set in mind as you design individual icons. Ask yourself if each new design fits into the overall narrative of the set. If something feels off, revisit it until it aligns.

Your Consistency Checklist

Ready to dive in? Keep all these principles in mind to make sure every icon in your set satisfies the same criteria:

• Subject matter: You should design your icon set for one singular, unifying topic – like “principles of physics” or “marsupials of Australia.” Don’t mix and match disparate concepts within a single set. Bonus tip: design for specific topics that are unique and underrepresented! More specificity and specialization means your icon set will stand out from the rest.
• Style: Outline or filled, curvy or straight, detailed or minimal, hand-drawn illustration or geometric vectors.
• Stroke: Line weights should have the same level of thickness throughout.
• Fill: If your icons are fully or partially filled, each should have the same balance of white space.
• Corner radius: The choice to have sharp or rounded corners within shapes should remain consistent, and in most cases it’s a good idea to use the same corner radius or mitre value throughout.
• White space, padding, and grid system: It’s a good idea to start every icon set with an icon grid that you use to guide your design, with symmetrical guides and buffering white space around every shape. This also ensures that the scale and proportion of all your icons remains consistent – i.e., they should have a uniform height and width. For the end user, it’s easier to work with icons that are scaled up to the edges of their bounding box – not scaled down and left with excessive padding.

In the end, a strong icon set isn’t just about creating beautiful individual icons—it’s about building a complete, harmonious package that provides users with a visually coherent toolkit for their own design process. By focusing on style, consistency, subject relevance, and scalability, you can create icon sets that not only stand out but also deliver functional and aesthetic delight.

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