The Fidelity Curve

How do we choose which level of fidelity is appropriate for a project?

I think about it like this: The purpose of making sketches and mockups before coding is to gain confidence in what we plan to do. I’m trying to remove risk from the decision to build something by somehow “previewing” it in a cheaper form. There’s a trade-off here. The higher the fidelity of the mockup, the more confidence it gives me. But the longer it takes to create that mockup, the more time I’ve wasted on an intermediate step before building the real thing.

I like to look at that trade-off economically. Each method reduces risk by letting me preview the outcome at lower fidelity, at the cost of time spent on it. The cost/benefit of each type of mockup is going to vary depending on the fidelity of the simulation and the work involved in building the real thing.

  1. ​Four levels of fidelity​
  2. ​Time to build versus confidence gained​
  1. Four levels of fidelity

    Suppose we have four levels of fidelity…

    • Rough sketch (on paper or an iPad)
    • Static mock-up (eg. Photoshop or Sketch)
    • Interactive mock-up (eg. Framer, InVision)
    • Working code prototype (HTML/CSS, iOS views)

    Depending on the feature you’re working on, these levels of fidelity take different amounts of time to create. If you plot them in terms of time to build versus confidence gained, you could imagine something like a per-feature fidelity curve.

    The sidenote here I think is actually the most important takeaway, and explains perfectly my feelings on 'low fidelity prototypes' — why bother?

    I didn’t include wireframes in the list because we don’t make them at Basecamp. For us a rough paper sketch is the same as a wireframe, without the extra time wasted on sharp lines and shiny presentation.

  2. Time to build versus confidence gained

    Image from m.signalvnoise.com on 2021-09-05 at 1.57.04 PM.png

    Take a simple CRUD web UI, where you’re just navigating between screens. It doesn’t take much more time to build the real version than it does to mock it when the design is simple. If you were to build out an interactive mock first, you would end up spending twice as much time in total without gaining much out of it.

    Contrast that with a complicated Javascript interaction. Or a native iOS feature that requires programmer time to build out. If it takes substantially more time to build the real code version, then it may be smart to do an interactive mockup first.