Low fidelity vs. high fidelity prototyping comparison guide

When used wisely, prototypes help teams save valuable time and resources while also delivering a much better user experience. Prototyping allows designers to test the feasibility of their ideas, detect problems, and make necessary adjustments–all without having to invest the monumental effort of building a complete product. Without proper or enough testing, it's very likely that some features would fall short of expectations once the public is actually engaging with the product. These are the kinds of difficult growing pains that any user experience (UX) design team will try to avoid at all costs.  

Prototyping can range from just a very basic sketch of the initial ideas to something much more functional. It can be organized into two broad categories based on how developed the prototypes are: low fidelity and high fidelity. Both of these levels will play a significant role at different stages of the development process. The best prototype will depend on the needs of the project at that specific moment.  

In prototyping, fidelity relates to how closely the prototype looks and behaves compared to the finished product. Low fidelity prototypes offer less detail and interactivity, so they're generally fast and easy to produce. High fidelity prototypes are able to simulate a much more accurate representation of the final product's visual design and functionality, allowing for better testing and more detailed feedback. Ideally, high fidelity prototypes are realistic enough to test whatever variations or design questions a team may have with how users will interact with the interface. 

Product design teams will determine the appropriate prototype fidelity depending on factors like the completeness of their current design, specific goals at that stage of the project, or the available time and/or resources. Sometimes, both low fidelity and high fidelity prototyping can come into play.  

The lowest fidelity prototype can be as simple as a rough sketch that's been either drawn on paper or designed digitally in software. This prototype approach is all about function rather than form, so it would tend to show representations of design elements in more simplistic forms like rectangles or lines in a blue-print-like style (wireframes).  

Different steps in the application's workflow can be shown with specific features depicted through the series of sketch screens. Low fidelity prototypes are simple, low-tech, and quick to bring together. Their purpose is to turn a general concept into something that's tangible enough to analyze, test, and develop further, especially during the earliest stages of the design process. 

There's not much visual design at this stage but the prototype can still represent the most important elements of the idea. Their emphasis is on collecting feedback that can help build the concept into a great product that solves a specific set of problems. 

Common techniques for creating low fidelity prototypes today are: 

• Wireframes depicted in digital form that can be made interactive

• Digitally sketching wireframes in programs such as Invision’s Freehand

• Hand-sketched on paper in exercises like Crazy 8s

• Hand-sketched on dry erase boards to brainstorm flows as a team

• Drawn out on napkins in cafés

Paper prototypes 

Paper prototypes can be sketched on paper or a whiteboard, but will often be created digitally with drawing software or an app. In any form, paper prototypes present a draft of different screens in the product's layouts, including user flows and interactions. A test participant can engage with a paper prototype by following steps that emulate how they would actually use the product. 

None of the elements in a paper prototype are clickable so it takes some imagination to interact with the design. However, these basic mockups are great for quick idea-sharing, fleshing out initial concepts, and visualizing the overall structure. Most importantly, this technique allows designers to make changes extremely quickly in response to feedback and launch experiments that turn costly changes into very little investment or effort.  

Clickable wireframes 

The next notch above paper prototyping is clickable, which offers a more realistic experience with elements of the final product, especially the interactivity. Clickable wireframes are designed to let users click on buttons to jump between screens that reveal a skeletal model of the app or website. 

For example, they can begin with a log-in button, which would take them through to the next screen with more options for other actions they can take. Clickable wireframes are still low fidelity and relatively far from the final product, so they don't require a major investment of resources. However, they can still be interactive and provide the ability to test the behavior aspects of the user flow. 

During the early stages of a UX design project, low fidelity prototypes allow teams to move quickly between an initial idea to the implementation stage. However, there's a ceiling to how far projects can advance with user testing with just these basic prototypes. 

Advantages of low fidelity prototypes 

• Easy and collaborative: They don't require much technical ability or special skills, so members of the team that aren't designers can still participate and contribute.

• Fast and flexible: It's possible to explore lots of different ideas very quickly, including testing variations of the same concept and making quick adjustments.

• Can evaluate core concepts: Low fidelity prototypes don't have too many visual elements or other details that can influence the user's experience, so they're helpful for getting feedback on the fundamental ideas behind the product, including whether such a product is even needed in the first place.    

• Very inexpensive: One of the biggest advantages of a lower fidelity prototype is being able to dive into a new concept without spending a lot of resources, allowing the team more freedom to fail, try again, and fail some more if necessary.

Limitations of low fidelity prototypes

• Not as accurate: The basic layouts and functionality offered by a low fidelity prototype are likely more limited and basic, requiring the user to do more work and leaving gaps as to how a higher fidelity prototype or final product might work.

• Limited interaction: Depending on which software you use to develop a  low fidelity prototype, some interactivity may be limited. Often, more dynamic features like search, dropdowns, or maps will not be active in the way of a real product, so it requires imagination for users. This can sometimes lead to user feedback being muddled with comments about how the prototype software works rather than how the flow was intended to behave. 

High fidelity prototypes are appropriate when the product is closer to being finalized and user testing needs to become much more rigorous. They're meant to present a design that looks and feels as close to the final product as possible, with the right visuals, content, buttons, number of screens, and navigation style. 

Designers can work with developers to create an immersive, interactive experience by adding transitions and animations that demonstrate all the product features that need to be tested. As an example, for an ecommerce product, the high-definition prototype would have images of the items for sale and walk the user through a complete checkout flow, with screen transitions that simulate each step in the process. The design can even include elements such as showing when a new item has been added to the user's cart. 

High fidelity prototypes are much more refined, allowing users to provide real feedback about how they interact with the product and what could be improved. These models are also functional and attractive enough to be presented to other stakeholders, like product managers, clients, or potential investors. 

There are several different techniques for creating a high fidelity UX product design prototype, but the most common are:

• Pulling from an existing style library built in Sketch or Figma

• Using tools like Lucidchart, Axure RP, or OmniGraffle

• Development teams or UX Developers can also create prototypes that are essentially just variations on top of existing code-bases

Digital prototypes

Digital prototyping software is the most popular option for building a model that faithfully recreates the final product, and can also be previewed in a web browser or mobile device. These complex models are able to demonstrate real-time behavior, rich colors, and an accurate sense of what users would actually experience. Many elements are clickable and the screens are connected to each other as intuitively as possible, allowing the user to really interact. 

The layout and other visual details are also true to size and stylistically accurate for the look of the final product. Overall, these specialized tools offer designers a range of features that can bring the design to life. While digital prototypes are not fully functional, they provide a seamless experience that makes it possible to test concepts and features with a high degree of accuracy. 

Coded prototypes 

This prototype technique is less common because it's a much bigger time commitment and requires advanced coding skills. Coded prototypes can work well for user testing of a product that's very far along in the development process and almost fully functional. As the highest fidelity prototype, these models are an extremely realistic representation of the finished product, both visually and in how it behaves. 

The result is a very rich sandbox for users to explore different features and provide valuable feedback. Ideally, a coded prototype would also lay down some of the groundwork for building the finished product. However, the point of prototyping is to get quality testing from users, not to actually build usable code. It's wise not to over-invest by creating coding for a project that ultimately won't go forward.  

High fidelity prototypes are invaluable for the advanced UX design process, but they can come with very significant costs. More mature product teams will often come with mature style libraries, allowing an almost drag-and-drop-like experience for designers to easily make high fidelity prototypes the most reasonable and quickest solution. 

In fact, once the initial sketches and brainstorming are through, lower fidelity mockups generally won’t make sense for these teams. But for newer teams, such as start-ups, embarking on a high fidelity prototype shouldn't be taken lightly. 

Advantages of high fidelity prototypes 

• More reliable user testing: High fidelity prototypes are much closer to the real thing, which offers very valuable insights from the user testing process and increases the chances of discovering serious weaknesses in the design. The interactivity of these models is close enough that users can engage in a way that's very natural and similar to how they would use the real product.

• More accurate adjustments: High fidelity prototypes are detailed enough to provide designers with valuable information about the nitty-gritty of a proposed design, including specific interactions, transitions between screens, button color, and other components that may need to be fine-tuned.

• More polished presentation for stakeholders: Creating an appealing, semi-functional prototype that closely resembles the finished product can help stakeholders or investors understand an intended design and get on board with the project.

Limitations of high fidelity prototypes

• Much more expensive: Depending on the type of product being created, high fidelity prototyping may require coders, a graphic designer, a copywriter, and more, which can all add up. Without an existing design library to pull from, the higher the fidelity, the higher the costs involved.

• More time-consuming, less flexible: Coded prototypes are likely to take an especially long time to produce, but even digital prototypes will require a major time investment to tweak all the different elements. Modifying these prototypes in response to feedback can also take significantly longer than with low-fi models, so it's not as flexible of a process for designs that still need substantial changes.

• More risk of bias: Bias is always a lethal risk of research. It’s only natural that increased effort put into a prototype comes with a higher risk of bias. Sometimes the creators of the prototypes won’t want to make changes or tweaks to something they’ve come to like or identify with. It’s also safe to assume the more time a team spends on a flow, the more biased they are that it solves the problem since they know deeply how it works. Minds become harder to change than pixels or code.

• Require more specialized skills and tools: Compared to low-fi prototypes, which are very easy to create, there are many more complex skills involved in building high fidelity versions. 

When thinking about the right approach for which prototyping is best for any project, one broad guideline is that the appropriate level of fidelity will depend on factors like the project's needs and what resources are available during every stage of the process. The three main questions to ask will be: 

1. How much detail and precision is necessary for this project right now?

2. What is my financial budget and how much time do I have? 

3. What existing designs or code has my team already developed?

Low fidelity prototypes can help you quickly get a sense of basic concepts and begin testing the idea before committing to its development. High fidelity prototypes can be useful to help advance an idea that's already been refined up to a certain point and now needs accurate user testing to help the project land on the final designs. Most UX products just need to be verified with several rounds of feedback and tweaks. 

The fidelity of the prototype doesn’t matter as much as what you learn from it. It's worth remembering not to put too much effort into a slick, beautiful high fidelity prototype that's not really necessary at your current stage in the design process. Ultimately, prototypes are only valuable to the extent they can help you move forward in the project.

Testing early and often with prototyping is the best protection against making major mistakes or missing opportunities that will affect the user experience. At the earliest stages, prototypes can help refine initial ideas and help your team decide which ones are worth pursuing. Based on the project's specific needs and goals, both low fidelity and high fidelity prototyping can be crucial to gathering the user feedback necessary for building a great product.