Different people make different choices, but everybody should let their sleeves of the shirt pop out a little bit. How much exactly? That is where you can let your creativity kick in. You should always take two aspects in account; the sleeve length of your shirt and the sleeve length of your suit.
A sleeve is defined as something that covers your arm, not your arm and hand. From this basic principle, we can continue our story.
Notice that the sleeves of a Double-Cuffed shirt tend to stick out more than a Single Cuffed shirt. The reason for this is that the sleeves of the Single Cuffed shirt fall on your wristbone and the sleeves of the Double Cuffed shirt stick out a little bit further than your wristbone, almost at the beginning of your hand. So what is the correct sleeve length for a shirt? With the Single Cuffed shirt falling on your wristbone, it should show about 0,50 inch (or approximately 1,3 cm) underneath your suit’s sleeves. The Double Cuffed shirt is allowed to show more, think about 0,80 inch (approximately 2 cm).
The second aspect to take in account is the sleeve length of the suit. These sleeves should always end at the wristbone, with your arm at rest. This way the shirt has enough length to stick out underneath it. Please, never, ever demonstrate that your sleeves are too short by sticking out your both arms. First of all, you will never assume a position like that, unless driving a car. Secondly, you are not allowed to wear a jacket whilst driving a car.
I personally think that it is a great detail to have your shirt pop out a little bit underneath your sleeves. Especially when you are wearing a coloured shirt, the matching colours of your combination are a great additive to your appearance. Wearing your sleeves on the correct length also shows that you are wearing a suit tailored to your sizes and not some suit in somebody else’s size. So if you have your tricks up your sleeve, visit a tailor, and make sure you wear your heart on your sleeve.