Cuff 1.5 in. (~3.8 cm)
Cuffs serve both functional and aesthetic purposes. It adds weight to the hem, allowing your trousers to fall nicely. This is important if you're choosing our lightweight/light-midweight fabrics, as it may float about in the absence of a cuff.
However, practical considerations can sometimes give way to sartorial considerations. Cuffs carry with them a certain appeal of elegance, and can flatter you when it's done in the right proportion. If you're around 5'5/1.65m, 1.5inch cuffs is a good starting point.