A full or double bed is 54 inches by 75 inches in North America, Australia and the United Kingdom.
In the United States, certain beds are often referred to as "twin" and "full." In England, these bed sizes are referred to as "single" and "double."
When buying sheets for a full or double bed, the sheets may have "full" or "double" listed as its measurements. Either will fit, but some people choose queen-size sheets, which allow more room for the sheets to wrap around the mattress.
Twin mattresses are shorter than full or double beds. They are 39 inches by 75 inches. Queen beds are 60 inches by 80 inches, and king-size beds are 76 inches by 80 inches.
While being more roomy than a single or a twin, a full or double bed is the same length as a twin and only 15 inches wider, making it slightly narrow for two adults.