Your project instructions call for two yards of 60" wide fabric, but the fabric you want to use is 45" wide. Hmmm... attempting to dredge up that old math lesson in proportions is probably not going to happen on the fly. Instead, print out our handy conversion chart for those times you don't have a pattern envelope with a yardage conversion table.
Remember, these are general estimates. If your fabric has a big motif, a large repeat or is directional, it's best to buy extra. When working with large repeats, the rule of thumb is to buy the pattern's suggested amount of fabric plus enough extra to cover one full repeat.
Other extra-fabric situations include if you are cutting fabric on the bias or if your pattern includes extensive fussy cutting for matching pockets and the like.
When in doubt, add an extra ½ yard. It's always better to have a bit more than not enough. Poplular fabrics can sell-out in the blink of an eye. It's best to get a bit more than you need when it's readily available.
Sew4Home Fabric Yardage Conversion Chart in Adobe Acrobat format (36KB)