It is important to know whether a throw will barely cover your lap or could easily cover a compact car. It is even more important to know whether a sweater will actually fit you. Most patterns include Size and/or Finished Measurement sections to indicate the expected dimensions of the finished piece.
Sizes are specified in very general terms, such as S (small), 1X (extra large), and 0-6 months. Finished measurements are more specific and should be carefully considered. A garment could have an oversized, relaxed, standard, tight, or very tight fit. An oversized garment has a finished chest measurement 6 or more inches larger than the actual chest measurement of the wearer. For a relaxed fit, the finished chest measurement is 4 to 6 inches larger. For a standard fit, the finished chest measurement is 2 to 4 inches larger, for a tight fit the finished chest measurement is 0-2 inches larger, and for a very tight fit the finished chest measurement can be the same or less than the actual chest measurement.
The designer of a garment intends a certain fit and indicates this through the combination of size and finished measurements. The actual chest measurement for a S (small) woman is 32-34 in. and for a M (medium) woman is 36-38 in. If a designer specifies size S (small) and the finished chest measurement is 40 in., because the finished measurement is 6 in. or more larger than the actual chest measurement, the intended fit is oversized. On the other hand, if a designer specifies size M (medium) and the finished chest measurement is 40 in., the intended fit is standard.