A king-size loft bed is certainly an unconventional piece of furniture, but it saves more than 40 square feet of floor space. This project will take a few hours. These plans are for pine and plywood, the cheapest woods available, but you can substitute more expensive lumber for a fancier finished product.
Here's another King-size loft bed. Looks like they use this room as an everything room, for a studio apt. perhaps. I see bed, desk (under bed), and sofa. This could also be just the bedroom if you don't have room for an office elsewhere chez vous.
Bed Plans; easy to build, require minimal equipment, and use regular 2x4 construction lumber, they correspond to the four standard mattress sizes used in North America, plans for twin, standard double (full), queen, king, and bunk beds, plus plans for day beds and fancier head and foot boards for double standard (full) and queen