When designing apps, it’s easy to assume users interact with them in ideal conditions: perfect lighting, full attention, and comfortable surroundings. But the reality is very different. People use apps while commuting, sitting outdoors, or in challenging environments—and some users may even have physical or visual impairments that affect their experience. Testing apps under these less-than-optimal conditions is a practical way to uncover flaws in usability and ensure your design works for everyone.

One way to identify problem areas is to simulate real-world challenges while trying to use your app. Try using it without glasses if you typically wear them or wear overly strong glasses to distort your vision. Place your face close to the screen and see how comfortable it feels to interact with your design under extreme proximity. These experiments can reveal whether your app supports users with varying visual needs and highlight areas where readability or functionality needs improvement.

Lighting conditions can also drastically impact usability. Lower the brightness on your screen to mimic usage in dim environments or test your app outdoors in direct sunlight, where glare makes viewing difficult. Another option is to enable a black-and-white or grayscale filter on your device and evaluate whether your app’s key elements remain functional and clear.

It’s important to consider how adaptable your app is to font and zoom changes. Shrink the text size or zoom out to test for readability when accessing compact displays or small screens. Then reverse this by enlarging the font or zooming in to check whether users with impaired vision can comfortably navigate your app.

Movement and accessibility challenges can offer additional insights. Try using the app with just one finger on each hand or only one hand altogether. This can mimic how your app might be used during multitasking scenarios, like holding onto a bag or steering on public transport. These tests also help highlight pain points for users with disabilities or limited mobility.

By running your app through these conditions, you’ll learn what works and what doesn’t, uncover pain points, and identify areas for improvement. Small adjustments—such as improving text legibility, tweaking button placement, or ensuring responsiveness to varying screen settings—can have a big impact on how user-friendly your app feels.

Testing under challenging conditions is more than just a design exercise; it’s an opportunity to build something adaptable, usable, and inclusive. Push your app to its limits during development and prioritize accessibility from the start. If it still works when you’re struggling to use it, then you’re on the right track to creating an app that will work for everyone.