The most common business card size is 84 mm by 55 mm, or 3.5 inches by 2 inches. You can go bigger, but if you do your cards are less likely to be kept. If you go smaller, you have a better shot, as long as they still fit in a typical card folio. Any non-traditional size is going to cost you more money.
Do not forget that the back of your business card is prime real estate to make use of. Add a business card background design that’s meaningful to your brand or business. Showcase images of your work. Or give a special offer, promote a high value giveaway, or direct prospects to an engaging landing page.
A professional business card needs to fit the branding of your business, display your logo prominently, and highlight your website and contact details, so the people you connect with can find you online, on social, or via email.
If you met two individuals and one was scrambling to find a pen and something to write on and the other person simply pulled out a business card, who would you want to do business with? Showing that you are prepared at all times is a great indicator that you are professional.