Nearly all hotel rooms in the United States have some type of tub in their bathroom. In general, the standard size of these are 5 foot long.
The standard contact sheet size used in photography is 8x10 inches.
"Standard tub" is too vague. More information is needed, especially what the 'tub' is used for? Tub of icecream? Tub of lard? Bathtub? etc.
The standard size of the nut used on a bike's rear axle is typically 15mm.
The standard shogi board size used for official matches is 9x9 squares.
The standard birth certificate size used in most countries is typically 8.5 inches by 11 inches, which is the same size as a standard piece of printer paper.
The size of a Standard video file depends on the size of the media used to create it.
The standard dowel size used for assembling furniture is typically 1/4 inch in diameter.
The standard pedal thread size used in most bicycles is 9/16 inch.
The standard unit of measurement used for determining the size of a bath is typically in feet or inches.
The standard check size used for most printed checks is 6 inches by 2.75 inches.
The standard size of a Schrader valve used in most bicycle tires is 8mm in diameter.
The standard size business letter is called a #10envelope.