If you and your partner have similar sleep needs, chances are you don't need a split king. For instance, if you're both side sleepers who weigh between 130 and 230 pounds, it's likely you can both sleep on the same king size mattress. However, there are several scenarios in which you might need to consider a split king.
If you and your partner are different sizes or have vastly different sleep styles, you may not be able to compromise comfortably on firmness level. In that case, a split king bed can allow both of you to get the firmnesses you need. You and your partner might also have different temperature regulation needs that cause you to need different mattress materials.
Another big reason you might need a split king bed is if you have different ideal adjustable base settings. For instance, if one partner wants to lie flat while the other wants to adopt the zero-gravity position, you’ll need a split king to achieve that.