Music note stem length

Normally stems on music notes are exactly one octave in length (three and a half spaces).

STEM LENGTH = 3 1/2   SPACES

Another example of this would be:

Using this rule, multiple notes on a stave (staff USA) would look like this:

An exception to this rule occurs when notes are drawn two or more ledgers above or below the stave (staff USA). In this case, the stem is drawn to meet the third line: