Bed sizes vary to accommodate different needs and preferences. The most common sizes include Twin, Full, Queen, and King. A Twin bed is typically 38 inches wide and 75 inches long, ideal for children or small rooms. A Full bed, also known as a double, measures 54 inches wide and 75 inches long, providing more space for single sleepers or couples. The Queen bed is a popular choice for couples, measuring 60 inches wide and 80 inches long, while the King bed offers even more space at 76 inches wide and 80 inches long. Additionally, there are variations like the California King, which is narrower and longer than a standard King.