How long are three centimetres? Consider the tip of your thumb to visualise 3 centimetres (cm) or how large 3cm is. The average distance between the first joint in the tip is 1 inch, or 2.54 centimetres per inch. Therefore, 1 3/16 inches is approximately 3 centimetres, and 3 cm is somewhat longer than the normal thumb from the first knuckle to the tip.
Other visual depictions of the length of 3 cm include a dollar bill folded in half lengthwise, which measures around 3.2 centimetres, and the diameter of a quarter, which measures approximately 2.5 centimetres.