You don't have to buy a king bed when you have two twin beds you can put together. Store-bought products can help you convert two twin beds into a king bed in just a few steps. One product includes a belt that runs on the perimeter of the twin bed mattresses, which connects to itself at the foot of the bed to keep the mattresses together. A mattress topper gets rid of the dip in the middle, or you can pick up a special T-shaped foam centerpiece bridge that sits over the mattresses with the leg of the "T" between them to remove the gap.
Two Twins as a King
Standard dimensions of twin beds are 38 inches wide and 75 inches long. When joined together, they form a 76-inch-wide mattress that's 75 inches long. An eastern or standard king bed's measurements are 76 inches wide and 80 inches long, while a California king mattress runs 72 inches wide and 84 inches long. When you elect to use two twin beds as a king, you need to buy split-king bedding and sheets to ensure a good fit. If you have two extra-long twins at 80 inches long, you can use standard king sheets without worry.
Twin Bed Converters
Multiple companies sell converters that make two twin beds into a king bed. The biggest problem with some of these products is the gap in the middle between the two twin beds -- and the tendency for the beds to pull apart. The belt option includes an 8-inch-wide sheepskin panel that fits over the gap between the two beds when you add the belt that buckles the mattresses together. This product fits mattresses 80 inches long and 39 inches wide -- extra-long twins.
You don't have to buy a new king-sized bed frame as long as you ensure that the beds don't move apart in their twin frames. A low-tech way to keep two twin metal bed frames together is to use cable ties to lock the middle feet of the two beds together. That way, you can use the original metal frames, box-springs -- and even the headboards if desired -- without any extra expense. You can also get creative and to attach to the metal frames or the wall. You can also repurpose an old interior door into a king headboard.
The King-Size Bed Frame
A metal king-size bed frame can be used to hold the twin beds together as long as it contains a center support bar or slats that the inner edges of the twin bed box springs can rest upon.
When you have an open metal frame without the metal support, pick up pine 3- or 4-inch-wide slats that are as long as the two twin beds are wide. You'll need basically three to four slats to fit across the width of the metal frame to support the box spring and mattresses. You can add more if desired. Some stores even sell slatted bed bases as single units. If you don't want to use box springs, build a instead.