The banana rule: designing user interfaces following the natural curvature of the hand

Design is a fundamental aspect in every project aimed at providing a quality user experience. Among the design theories that can help create excellent products is the banana rule.

What is the banana rule?

The banana rule is a design theory based on the natural shape of the human hand. The rule states that user interfaces should be designed following the natural curvature of the hand when holding an object, such as a banana.

In other words, the banana rule suggests designing user interfaces to reflect the shape of the hand so that users can interact with the interface comfortably and intuitively.

Why is the banana rule important?

The banana rule is important because it helps to improve the user experience and user interface design. When user interfaces follow the natural shape of the hand, users will feel more comfortable and be able to interact with the product more smoothly and intuitively.

Additionally, the banana rule also helps prevent muscular fatigue and repetitive stress injuries, which can occur when users have to use uncomfortable or poorly ergonomic user interfaces.

How to implement the banana rule?

To implement the banana rule, designers should consider several factors. First, they should consider the position of user interface elements in relation to the user’s hand.

The most frequently used user interface elements should be positioned at the bottom of the interface, where the hand is naturally more curved, while less used elements can be positioned at the top of the interface.

In addition, designers should also consider the size of user interface elements. Elements that require frequent interaction should be large enough to be easily reachable with the thumb or fingers, while less used elements can be smaller and placed in less accessible positions.

Finally, designers should also consider the shape of user interface elements. Elements that require frequent interaction should have a curved shape, to follow the natural curvature of the hand, while less used elements can have more complex or geometric shapes.

How Airbnb implemented the banana rule: a tangible example

A concrete example of the application of the banana rule can be found on the Airbnb website. The site, which allows users to book accommodations worldwide, has a well-designed homepage that follows the natural shape of the hand.

At the top of the homepage, less frequently used user interface elements, such as the logo and navigation menu, are positioned to be easily reached with the thumb. In addition, the shape of call-to-action buttons, such as the “Book now” button, follows the natural curvature of the hand, making interaction more comfortable for users.

In the bottom of the homepage, on the other hand, the most frequently used user interface elements, such as the search bar and search filters, are positioned at the bottom of the page, where the hand is naturally more curved. Again, the shape of call-to-action buttons, such as the “Search” button, follows the natural curvature of the hand.

In this way, Airbnb has created an ergonomically designed homepage that follows the banana rule and offers a comfortable and intuitive user experience for users looking for accommodations. The application of the banana rule has certainly contributed to improving the usability of the site and creating a positive user experience.

Conclusions

The banana rule is a useful design theory for improving user experience and user interface design. By following this rule, designers can create more ergonomic and comfortable user interfaces that help users interact with the product in a more natural and intuitive way.

However, the banana rule should not be considered an absolute rule. Designers should always consider the specific context in which the product will be used, the target audience, and the product’s features.

The banana rule is just one of many factors to consider in user interface design, but it can certainly contribute to creating better products for users.

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