It can be measured in meters or feet and inches.
You find a tape measure and take the measurement across the door, then the length of it, then if necessary the thickness.
You measure its length, breath, height and mass. Then Density = Mass/(Length*Breadth*Mass) in the appropriate units.
Distance is typically measured in meters, while liters are used to measure volume of liquid. To measure the distance of a door, you would use meters. Liters are not relevant for measuring distances.
To accurately measure a door hinge, use a tape measure to determine the length and width of the hinge. Measure from the center of one screw hole to the center of the other screw hole to find the hinge's size. Make sure to measure in millimeters for precision.
In the US, doors are sold in inches. If you are measuring the door in order to bring in some furniture, any measurement of length - inches or centimeters - will work. It is in centimeters. That is more appropriate
The perimeter of a door is the total distance around its outer edges. To calculate the perimeter of a door, you would measure the length of all four sides of the door and then add them together. For example, if a door is rectangular with a length of 80 inches and a width of 36 inches, the perimeter would be calculated as follows: 80 + 80 + 36 + 36 = 232 inches.
Square measure is a measure of area it does not have a singular linear dimension. 200 squre yards can have an infinite number of dimensions so long as the product of those numbers equal 200 in the relavent unit of measure.
Length and Breath are terms used in golf. Length is the longevity of your swing, back to front. Breath is your breathing pattern during a swing, which should be kept constant.
Measure the length of your stride and call it S. Then walk from the curb to your front door on eh sidewalk and count the number of strides. Say it is N. Then the length is S x N = Length in whatever unit you measured your stride.
You will find the answer on Wikipedia.
length *breath
Length and breath or length and width.