Rule for feminine · die
-ung → die · 10.6%
Almost every noun ending in -ung is feminine (die) - it's one of German's most productive suffixes, showing up in over 10% of frequent nouns. It's usually built from a verb: die Richtung (direction, from "richten"), die Regierung (government, from "regieren"), or die Unterstützung (support, from "unterstützen"). Watch out, though, for a handful of words that only LOOK like they carry the suffix but aren't verb derivations at all: der Sprung (jump), der Schwung (momentum), and the compound der Vorsprung (head start) are masculine, because "-ung" is simply part of the word's root, not an added suffix. Overall the rule is highly reliable - just 3 exceptions out of 254 words - so you can safely bet on die whenever you see -ung at the end of a noun built from a verb.