There’s no universal ‘best color’ for a shopping cart button, but contrast is important. As a general rule of thumb, it’s a good idea to choose a color for your cart button that stands out from the background of your website.  One way to achieve this is to use colors that sit opposite each other on the color wheel. For example, if the background of the page is orange, then a blue ‘add to cart’ button should stand out and get more clicks as it’s directly opposite orange on the color wheel.