THESE are examples to help estimate amounts required for a specific garment.  Keep in mind, these are examples only but may offer some helpful information when designing your own pattern:

**Gauge is 5 1/2 sts. = 1" on #5 needles and each skein has 100 gram/205 yds. Plan 7-8 skeins for a long sleeved medium sweater

**IF a  70% Wool/30% Linen -- knits at 4-4.5 stitches = 1" on #7 or #8 needles.
AND 50 gm. skeins have 75 yards per ball OR 150 yards=100 grams
OR  cones run about 687 yards per pound. 
Plan about 1½ pounds for a long sleeve medium sweater.

**IF yarn  Gauge is 3 sts. = 1" on #11 needles WITH 100 gram/83 yd per ball.
 Plan 13 skeins for a long sleeved medium sweater, 17 for a long oversized jacket.

**Worsted weight alpaca with gauge of 5 sts. = 1" on #7 needles and 102 yards/50 gm. ball. Plan 14-15 balls for a med. long sleeved sweater.

** bulky weight yarn -- 100% Icelandic wool with 109 yards/3½ oz. ball. Stitch gauge is 14 sts. = 4" on #10 or #10½ needles.
 Plan 8 balls for a long sleeved medium size.

**100% mercerized cotton, cable twist, worsted weight yarn at 185 yards/3½ oz.  skein OR approximately 100 grams.
Gauge is 5 sts. = 1" on #7 needles.
Plan 8-9 balls for a long sleeved medium size sweater