Step 1
Assemble the full bed frame upside down. Instead of having the long arms on the side facing upward with the side rail guards up, place the side rail guards down to accommodate the larger mattress. The side rail guards are the 90-degree angle pieces of metal that stick up from the side rails and hold the mattress in place. Although assembly may vary, most bed frames have you lock the arms together by sliding the notches in place. Metal bed frames are made to convert their length for use with a queen. When selecting the notches, use the longer placement to extend the length for the queen mattress.
Step 2
Place the cross rail so that the leg faces the same direction as the downward-facing side rail guards. If one of the arms is shorter than the other, place it on top for added strength. Depending on the bed, the crossbars will either snap together or require screws or a clamp to hold them in place. Other beds may have a single bar that slides into notches on the side rails.
Step 3
Insert a glide assembly leg extender into the bottom of the leg on the crossbar. The leg extender comes with the queen converter rail kit.
Step 4
Twist the extender until it is secured in the leg and the bottom edge rests firmly on the floor. This leg adds additional support to the crossbar to safely hold your weight.
Step 5
Locate the series of holes along the side rails. The number of holes varies by bed frame, but each rail should have sets, one set on either end of the rail.
Step 6
Place a queen converter bracket against the top of the side rail, lining up the holes in the bracket with the holes in the side rail. The bracket looks like an "L" with a short foot. Place the short foot facing upward. Place the edge of the long side of the "L" flush with the inside edge of the side rail.
Step 7
Insert a bolt through a washer, into the top of the bracket and through the hole in the side rail. Twist a nut onto the bottom of the bolt and tighten it with a wrench. Do this with all the retainer brackets using a bolt, washer and nut for each assembly. Bolt assemblies should be included with your conversion kit.
Step 8
Set up your box spring and mattress as usual.