noun
length, extent
B1
'Länge' (die) means length or extent, referring to measurement (distance) or figurative extent (duration, scope). Plural: Längen. Regular feminine declension (die Länge, der Länge). Idiom: 'in die Länge ziehen' = to drag out. Not reflexive; no special auxiliary. Used both in everyday and technical contexts.
Examples
Die Länge des Tisches ist zwei Meter.
The length of the table is two meters.
In ihrer Länge unterscheiden sich die beiden Rohre kaum.
In terms of length, the two pipes hardly differ.
Die Länge des Tisches beträgt zwei Meter.
The length of the table is two meters.
Details
Mnemonics
Picture a measuring tape stretched along the object to show its Länge.
Sounds like English 'length' — almost identical pronunciation.
die: many German nouns ending in -e are feminine—imagine a ribbon (feminine) measuring the length.