Though all tape measures measure distance, length, width or height, the graduations — or markings — that subdivide the standard measurement of the foot are not the same on engineering measuring tapes as on those used by carpenters or do-it-yourself enthusiasts.
Standard Tape Measure
On a standard tape measure, the subdivisions of the foot are inches, while the inches themselves are subdivived by factors of four, usually 1/16 or 1/32 inch, as well as the larger units of 1/4 and 1/2 inch. This is sufficient for simple measurements, but doing calculations with values greater than 1 foot requires converting those measurements into inches first.
Engineering Tape Measure
On an engineering tape measure, the foot is not divided into inches, but into tenths, or larger factors of 10, such as 1/20. 1/30, 1/50 or 1/60. With this type of tape measure, values greater than 1 foot can be multiplied without first converting the value to another unit, particularly in the case of tenths of a foot. A 1 1/2 feet times two would be expressed as 1.5 times two, which equals three feet.
On an engineering tape measure, 1.5 feet is the same as 1 foot, 6 inches on a standard tape measure. Each tenth of a foot on an engineering tape measure is equal to 1.2 inches.