The length of a joint of casing has been standardised and classified by the API as follows:
Although casing must meet the classification requirements of the API, set out above, it is not possible to manufacture it to a precise length. Therefore, when the casing is delivered to the rig, the precise length of each joint has to be measured and recorded on a tally sheet. The length is measured from the top of the connector to a reference point on the pin end of the connection at the far end of the casing joint. Lengths are recorded on the tally sheet to the nearest 100th of a foot. Range 2 is the most common length, although shorter lengths are useful as pup joints when attempting to assemble a precise length of string.