Measure the width and length of your bed. In the United States, a twin bed is 39 inches by 75 inches, a full bed measures 54 inches by 75 inches, a queen bed offers 60 inches by 80 inches and a king bed delivers 76 inches by 80 inches. Terms such as "California," "Expanded," "Super" and "Grand" indicate a variation of the standard size, either in length or width. In addition, beds from other countries often differ in dimensions.
Measure the block's depth (the length of the spaces running through the block) and the width (the longest side). A standard concrete block measures 7.63 inches high, 7.63 inches deep and 15.63 inches wide. Divide the length of the bed by the width (rounding up, with a standard block, to 16 inches each) and the width of the bed by the depth of the block (rounded up to 8 inches when using a standard block) to find the maximum block count if you do not want underneath storage.
Adjust the block count to use fewer blocks, to ensure the frame does not extend beyond the bed, if you choose a solid frame. Any excess block material, sticking out from under the mattress and foundation, will create rough, hard surfaces that you may stumble, scrape and bang against.
Mark and cut a sheet of plywood to match the size of your bed. Use an additional sheet if your bed is larger than 4-by-8-feet (the size of a sheet of plywood). Sand the edges smooth to eliminate splinters and jagged spots.
Lay a floor covering over your floor if you have wood floors or any surface that may become abraded or damaged by the concrete blocks. Additional plywood sheets, cut to size, plastic sheeting, fabric, felt, and old sheet -- any handy material that will cover the floor and prove stable is suitable.
Arrange the concrete blocks, solid sides facing up and down while the holes face sideways, around the area you will place your bed. Place the corner blocks first, then work from the inside of the frame out, spacing the blocks as desired to create storage space beneath the bed. Use at least one block every three feet for proper support..
Set the plywood on top of the concrete blocks, butting the edges together if more than one sheet is used. Check the edges of each side of the bed to make sure the blocks do not extend past the wood. If they do, remove the plywood and adjust the blocks. The plywood protects your mattress or box springs as well as distributing weight evenly across the blocks.
Spread a dust ruffle over the entire bed frame, or choose a unique finish. Painting the concrete gives a modern feel, or fabric glued to the plywood edge is another choice. Use the holes in the concrete blocks to access storage beneath the bed, when finished.