Doors come in standard sizes, with easy-to-understand size ratings. A 2-6 door is 30 inches, that is, two feet (2) plus six inches (6). You add the two feet, ie: 24 inches, to the 6 inches, and you get a 30-inch door.
You won't find doors much smaller in modern homes than a 2-6, but if you’re replacing a door on a travel trailer or some older model mobile homes, you might find a 2-0 door on a hot water closet.
The standard entry door is a 3-0, which is three feet, or 36 inches wide. Building codes require outside access doors to be this large at a minimum. A 36-inch door will allow furniture and appliances to fit through them, though they may take a bit of ingenuity in tilting and turning an odd-shaped piece of furniture through the door