How to Cut 200″ of Bias Tape Out of a 16″ Square of Fabric

In designing the Lemon Bay Doll guitar and banjo gig bags I decided to use custom bias tape to bind the bags. Problem was I was going to need a lot of it – 48″ to 56″ for each bag! If you’ve made bias strips, you know it’s no big deal to cut a small bit for a sleeve or pocket edge. But 56″ for one bag? It seemed like there had to be a clever way to make long lengths of bias strip without having to sew a bunch of short pieces together.

There is!

Everyone has probably heard the legend of Betsy Ross and her 5-pointed stars:

When asked by George Washington and his associates to create the American flag, Betsy suggested they use five-pointed stars instead of the six-pointed ones in their design. “Those would be too difficult to make!” they protested. Betsy picked up a small square of fabric, folded it skillfully, and made a single snip with her scissors. Opening up the folded fabric, she presented to her awestruck audience a perfectly symmetrical five-pointed star. They were so impressed with this feat of seamstress magic that they enthusiastically accepted her proposal.

I was equally impressed after a quilting friend of mine showed me how to make yards and yards of bias strip from one small square of fabric, two seams and two cuts. Here’s how you can accomplish this feat of seamstress magic to make 200 inches of custom bias strip out of a 16” fabric square.

For my gig bags I wanted a 1 ¼” bias strip which I could then fold to create double-fold bias tape. To begin, I cut a 16” square. It really needs to be a square square, on grain, so use a T-square if you have one. The square edge of a table will work in a pinch.

Next, mark the top and bottom edges, then the left and right edges. I used different color pins but making “x” and “o” marks on opposing sides with a pen (right near the edge) works too.

With the fabric right-side up, draw a diagonal line from the bottom left to the top right. Cut on this line making two triangles, A & B.

Move triangle B to the left side of triangle A so that the marked left and right edges are next to each other. (Mine are marked with the pink tulip pins)

With right sides facing, pin the left and right marked edges together. Overlap the edges ¼” to adjust for your seam allowance.

Sew the pinned edge with a ¼” seam allowance and press the seam open.

On the back side of your fabric, mark the width of your bias strip and draw straight lines across the length of your piece. I used pins to mark out every 1 ¼” and then drew lines with a marker.

Okay. Here’s where things get a bit tricky but it really isn’t that difficult once you get your head wrapped around it. We are going to make a tube out of this parallelogram. Take your marked piece and turn it so the right side is up. Fold in the corners so your marked edges (mine have the green tulips on them) come together.

Our lines are matching up nicely but if we cut now, we’d just have a bunch of short strips that still needed to be sewn together. What we want to have is a line that spirals around and around our tube so we just have one continuous cut to make. To do this, we shift our edges over one row.

Can you see what is happening here? Pretty neat, huh? If not, hang tight. You are about to be amazed.

We have one more seam to make. With our fabric shifted over the one row, we need to pin these two edges together so that our lines will match up after we make our seam. With right sides together, pick a line near the middle and put a pin through the line, ¼” from the edge. Now match up the other edge so that same pin goes through the line on that side, also ¼” from the edge.

Pin the rest of the lines in the same manner, working from the middle out. This is a somewhat awkward shape to work with but as long as your pins are going through the lines on both sides, you are good. Take this piece to the machine and sew a ¼” seam, pressing the seam allowance open when you are done.

Now you have an offset tube with one continuous strip! Starting at the bottom right, begin cutting on your line and spiraling around and around until you have . . .

… approximately 200 inches of bias strip! After my strip was cut, I used a ½” bias tape folding tool to make my double-fold bias tape.

There you have it! 200″ of bias strip out of a 16″ square of fabric. There must be some really cool math in there but we’ll leave that to the mathematicians to figure out. I’d rather just go on performing more feats of seamstress magic. How about you?

  1. Wow! What a great tutorial. I’m going to try this in the near future.

  2. Thank you for this wonderful tutorial!

  3. An amazing feat of ingenuity. I wonder how it was ever thought up? Thanks for the information!

  4. Great tutorial! Thanks for posting!

  5. Ok I am truly amazed!!!!

  6. I learned this in quilt class. I am so glad you shared this is such an easy to follow way. I had forgotten some of the details to make it work!

  7. Wow What a great tutorial .I will be trying this out.
    Thanks for the wonderful tips.

  8. Oh my gosh i learned a new technique. Thanks

  9. Thank you for your kind comments, everyone. So happy you find this helpful. I was intrigued when I first saw it, too. Its even more amazing when you actually do it – you appreciate the geometry hidden in it.

  10. I like to rip my fabric, that way it is a perfectly square and exactly on grain. Just iron afterwards since the ripped sides get a little stretched.

  11. I love this technique!!! It really does feel like magic. Thanks so much for sharing.

  12. Wow! SO COOL!! It’s great that you’re able to get so much out of one square of fabric! Thanks so much for sharing <3

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