No rule for this one
No ending or word group predicts the article of Hemd. Learn it as a pair and say it out loud: das Hemd.
das Hemd
It's das Hemd. Hemd is neuter, plural die Hemden.
Ich brauche ein Hemd.
I need a shirt.
Ich trage ein Hemd zur Arbeit.
I wear a shirt to work.
No ending or word group predicts the article of Hemd. Learn it as a pair and say it out loud: das Hemd.