You can easily make a king from twin mattresses. However, the standard size for an Eastern King size mattress is 76 inches wide by 80 inches long, while the standard-size twin is 38 inches wide and 75 inches long. This means your two twin-sized mattresses together are going to be the same width as a king-size mattress but 5 inches shorter. However, if you use twin extra-long mattresses, the dimensions will be exactly the same as those of a king-size mattress.
Place the king-size box spring or two twin-sized box springs on your bed frame.
Place the two extra-long twin mattresses on top of the box spring.
Run the rope, bungee or belt kit around the outside edges of the two mattresses to secure them together.
Insert material, foam or bridge kit into the gap between the two mattresses.
Place the egg crate mattress pad on top of the mattresses. This will help disguise the space between the two mattresses and make it more comfortable for anyone sleeping in the middle of the bed.
Place the fitted mattress pad over the egg crate mattress pad to further disguise the combined mattresses.
Make the bed using your king-size sheet set.
Combining two twin mattresses into a king bed is a good option for couples who want to sleep together but have different mattress needs for a good night’s rest. Flipping your mattress to maintain it will be easier with two twin mattresses than with one large king-size mattress.