There is a calculator on the Sailrite website. https://www.fabric-calculator.com/main-menu.aspx More on reddit.com

It depends on the final with needed. You need to remember you have to calculate or it's even allowance times to Plus the circumference of the piping cord. Then you do all the math to calculate how many yardage you need per the width of fabric. Here's a handy dandy set of formula With that being said, technically, you need about another yard of fabric if you're doing 2 in bias strips. Technically, three quarters should give you enough fabric. Here's a tutorial, YouTube . I saw you technically because generally upholstery fabric is bulkier and you may not like the extra amount of seams cutting from a smaller Square versus the hole width of the fabric. I have also work on some cushions with piping and they didn't bother to put the fabric on the bias. So you could in theory get away with half a yard of fabric that is at at least 37 in wide, if you need 2-in wide strips. More on reddit.com

Here is a conversion chart. Just make sure that the pattern pieces aren’t 60” wide (or 30” x 2). For instance, a full cape will probably be wider than 45” and it won’t drape right if you have to patch 2 pieces together. I hope that makes sense and I hope that is what you are asking. 😁 https://www.thesprucecrafts.com/fabric-yardage-conversion-chart-4145768 More on reddit.com

Really depends if you want to railroad the fabric or have seams in the top and bottom panels. Here's some quick numbers Railroaded: 5 yards How to cut- Two 89x22" long panels (top and bottom) in succession. Then cut your 4" boxing panel, then a 5.25" zipper panel, then your welting. In this way you will end up with a sizable waste strip that's about 20"x178" however you will have a seamless cushion. Up the roll: 3.5 yards How to cut- Two 54x22" long panels (top and bottom) stacked. Four 18.5x22" panels (the triangle shaped sides) stacked 2 at a time. Then three 4" boxing panels. Then one 5.25" zipper panel. Then cut however many welting strips you need. In this way you save some fabric but you have to seam so many things. Conclusion. Just get a railroaded fabric and spend the extra money.😎 More on reddit.com