Don't have the yarn your pattern needs?

When starting a knitting project, I decide what is to be the next project and start browsing through my books, notebooks, etc. I keep a 3-ring binder of patterns I have downloaded or written. I also keep a notebook of patterns that I have changed in some way. The most common change is the needle size and the yarn I use. When I change those things, changes are usually necessary in the pattern as well. It seems I want to knit a pattern that calls for yarn I never seem to have, and goodness knows, I certainly don't need to buy more yarn. I have bookmarked this chart from The Fiber Gypsy compiled by Esther Bozak. It gives you yarn requirements. Do a sample, check your gauge and you should be able to adapt most patterns if you don't vary by too many levels; i.e. a fine yarn project won't look right in a bulky yarn but it probably will do just fine in a sport weight if you make the proper adjustments.

Yarn Type	Typical Gauge	Wraps/Inch	Yards/Pound*	Recommended Needle Size
Ultrafine (Lace or Baby Weight)	8+/inch 32+/10cm	18 or more	2600	00 - 2 2 - 3mm
Fine (Fingering Weight)	6-8/inch 24-32/10cm	16	1900-2400	2 - 4 3 - 3.75mm
Medium (Sport Weight)	5-6/inch 20-24/10cm	14	1200-1800	4 - 6 3.75 - 4.5 mm
Heavy (Worsted Weight)	4-5/inch 16-20/10cm	12	900-1200	7 - 9 5 - 6mm
Bulky	3-4/inch 12-16/10cm	10	600-800	10 - 10 1/2 6.5 - 7.5mm
Very Bulky	2-3/inch 8-12/10cm	8 or fewer	400-500	13 - 15 9 - 10mm