The time to acquire a target is a function of the distance to and size of the target.

As I dive deeper into UX design, each new principle I learn reshapes the way I view digital experiences. One of the most eye-opening concepts I recently encountered is Fitts’ Law, as explained in Laws of UX. Initially, it seemed like a straightforward mathematical principle—predicting the time required to reach a target based on its size and distance—but the more I thought about it, the more I realised its profound implications on interaction design.

Fitts’ Law reinforces something that, as users, we experience every day but may not actively notice: the ease or frustration of navigating an interface. The core idea that larger and closer targets are easier to reach makes intuitive sense, but translating that into intentional design decisions requires deeper consideration. It’s not just about making buttons bigger; it’s about strategically placing them where users naturally reach for them.

One of the most striking realisations I had was how Fitts’ Law explains the placement of common UI elements. It’s no coincidence that mobile apps position essential buttons at the bottom of the screen—within easy thumb reach—or that desktop interfaces place frequently used controls in corners or edges, where the cursor can stop naturally. This made me reflect on past frustrating experiences with poorly designed interfaces, where tiny buttons or distant controls slowed me down, making interactions feel unnecessarily difficult.

Another aspect of Fitts’ Law that stood out to me is the importance of affordance and visual hierarchy. Larger buttons not only reduce selection time but also signal importance. This is something I’ve subconsciously noticed in well-designed interfaces—CTA buttons standing out, navigation menus positioned for efficiency—but now I can articulate why they work. It’s a powerful reminder that good UX design isn’t just about aesthetics; it’s rooted in cognitive and motor principles that shape human behaviour.

After reading this chapter, I find myself analysing apps and websites differently. I notice when designs align well with Fitts’ Law and when they don’t. For example, small close-together touch targets on mobile screens now stand out to me as usability pitfalls, and I better appreciate features like hover states and larger click areas that enhance usability.

Overall, Fitts’ Law has shifted my perspective on the seemingly simple act of clicking or tapping. It has reinforced the importance of designing with user effort in mind, making interactions feel natural and effortless. As I continue my UX journey, I’m eager to apply this knowledge thoughtfully, ensuring that every design decision contributes to a more intuitive and enjoyable experience for users.