They are meters to measure
Metres (in a built-up area), kilometres if across open spaces.
The easiest way is to simply measure across the pool as close to the center line as you can. Also, measure from several different spots to get the closest average. If you need the measurement for around the outside of the pool the you would want to measure the diameter (the distance from one side to the other) as close to the center as you can and multiply that distance (in inches) time 3.1415. For example, if the pool measure 12 feet across (144 inches) then the distance around the pool would be 452.3 inches. The pool liner supplier will most likely just need the diameter and the height of the pool.
metres
a millimetre
Miles is best.
They are meters to measure
Measuring Lake Erie from the Canadian side would probably be in kilometers. On the US side would probably be in miles.
miles or kilometers
You can measure the distance across the room using a measuring tape, laser distance measurer, or a ruler. Simply extend the measuring tool from one end of the room to the other to get an accurate measurement.
Because the distance across the Milky Way would be 588,000,000,000,000,000 miles.
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.
length
Distance
Distance
Metres (in a built-up area), kilometres if across open spaces.
The easiest way is to simply measure across the pool as close to the center line as you can. Also, measure from several different spots to get the closest average. If you need the measurement for around the outside of the pool the you would want to measure the diameter (the distance from one side to the other) as close to the center as you can and multiply that distance (in inches) time 3.1415. For example, if the pool measure 12 feet across (144 inches) then the distance around the pool would be 452.3 inches. The pool liner supplier will most likely just need the diameter and the height of the pool.