(Good for any yarny craft, and probably some others too.)
This is a variation of a conversation I had on Twitter last week.
Say you’re making a triangle shawl that’s going to have two stripes. How much more yarn will the second stripe take than the first? The stripes are going to be different sizes because it’s a triangle.
Here is a simple method to approximate the relative amounts of yarn.
Note: Exactly how much yarn is needed will depend on the thickness of your yarn, your gauge, and your stitch patterns. If there are different stitch patterns in different stripes, they will probably have different amounts of yarn for the same area.