The C in kopi c stands for Carnation, the evaporated milk brand, which tells you what is in it. About 25ml of evaporated milk at 35 calories, plus a heaped teaspoon or two of sugar at 50, plus the coffee itself at about 2. That is 87. A normal kopi with condensed milk is about 130, because condensed milk is evaporated milk with the sugar already in it and the uncle adds more sugar anyway. Kopi c is the lighter milk coffee by about 45 calories.
The word that matters is kosong. Kopi c kosong is 47 calories, and the 40 you save is pure sugar. It takes about a week to get used to the taste, and after that the sweet version tastes like syrup. Two kopi c a day, every day, is 174 calories. Two kopi c kosong is 94. Over a year the difference is about 29,000 calories, which is roughly 4kg of fat, from changing one word.
Iced versions are bigger. Kopi c peng comes in a taller glass and the stall adds more milk and sugar to fight the ice, so it is closer to 130. A large kopi c peng from a stall that uses the big plastic cup is about 160. If you want it cold, kopi c peng kosong is about 60 and does the same job.