So many knitting patterns (both hand and machine) are written for yarn that is no longer available. Here are some suggestions for successfully substituting yarn.
For coned yarn, use the Knit it Now Vintage Yarn index. The index is stuffed full of yardage and fiber content information. PLUS suggestions for replacements.
Use the Knit it Now Gauge Conversion Tool. Simply enter the pattern gauge and your gauge to find the conversion ratio. Multiply the pattern instructions by the ratio to create a custom pattern based on your gauge.
Use the Knit it Now Basics patterns. Identify the basic sweater shape used for your pattern. Create a custom pattern based on your gauge. Incorporate the "designer" touches from your printed knitting pattern .... with no math!