The word dimensions might bring a lot of sci-fi related topics into your head, and a big part of the reason why that is the case has to do with the fact that many sci-fi novels, TV shows and movies often involve travels into a supposed fourth dimension in some way, shape or form. That said, the manner in which dimensions are referred to in real life tends to have a distinctly practical flavor to them at any given point in time, and that is mostly due to the reason that they involve the lengths of each side of a given shape.
For example, the dimensions for Metal Business Kards often end up creating some kind of a rectangle. While there are also other shapes that tend to be used for business cards, suffice it to say that they are highly uncommon which means that there is no real benefit to you experimenting with them unless you have been in business for so long that you want to start trying to mix things up at the very least to a certain extent.
That means that your ideal dimensions for your upcoming business cards will likely be around 3.5 inches on two sides and 2 inches on the other two. It’s up to you whether you want the longer side to be viewed vertically or horizontally. The latter tends to be more common, but the former can also be a really amazing way to distinguish your card without having to get any expensive or garish design elements added to it. These dimensions are perfect for most businesses including those where premium cards are generally considered to be optimal.