The awrah for a man is from navel to knee:
1 – Abu Dawood (3140) and Ibn Maajah (1460) narrated that ‘Ali (may Allaah be pleased with him) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Do not show your thigh, and do not look at the thigh of anyone, living or dead.”
2 – Ahmad (21989) narrated that Muhammad ibn Jahsh (may Allaah be pleased with him) said: The Prophet (peace and blessings of Allaah be upon him) passed by Ma’mar when I was with him, and his thighs were uncovered. He said: “O Ma’mar, cover your thighs, for the thigh is ‘awrah.”
3 – Ahmad (15502), Abu Dawood (4014) and al-Tirmidhi (2798) narrated from Jawhad al-Aslami that the Prophet (peace and blessings of Allaah be upon him) passed by him when his thigh was uncovered and he said: “Do you not know that the thigh is ‘awrah?”
4 – al-Tirmidhi (2798) narrated from Ibn ‘Abbaas (may Allaah be pleased with him) that the Prophet (peace and blessings of Allaah be upon him) said: “The thigh is ‘awrah.”
you can wear some 3/4 trouser shorts like this brother is wearing;