There is no one definitive answer to this question. It can depend on a number of factors, such as the purpose of the shirt, the design itself, and the brand or company that is selling it. However, in general, most people agree that a design should be visible from at least 2-3 inches away from the shirt. This will ensure that it is seen by anyone who looks at it, regardless of their height or angle. Additionally, if you want your design to really stand out, consider placing it towards the bottom of the shirt. This will help it pop against the background fabric and make it more noticeable. Just be sure to keep in mind how far down the shirt goes when designing your logo or graphic!