وَإِذَا كَالُوهُمْ أَو وَّزَنُوهُمْ يُخْسِرُونَ
Wai tha k a loohum aw wazanoohum yukhsiroon a but when they have to measure or weigh whatever they owe to others, give less than what is due!1
 - Mohammad Asad
but when they give by measure or by weight to others, they give less than due.
 - Muhammad Farooq-i-Azam Malik
but give less when they measure or weigh for buyers.
 - Mustafa Khattab
But if they measure unto them or weigh for them, they cause them loss.
 - Marmaduke Pickthall
But when they have to give by measure or weight to men give less than due.
 - Abdullah Yusuf Ali