Trying out all the different stretchy bind-offs in these two tutorials brought out my inner scientist. Which of the stretchy bind-offs is the stretchiest? How stretchy is stretchy exactly? Can stretchiness be quantified? Yes, it can!
And here are the results: 12 bind-off methods ordered by stretchiness, starting from the least stretchy and ending with the most stretchy bind-off of them all. And because stretchiness is sometimes associated with the unwanted side effect of flare, I also measured how much wider the bind-off edge is when not stretched. (If you're interested in how I did the calculations, the details are at the end of this post.)
#12. Baseline: Standard Bind-off
I used the standard bind-off as a baseline against which all comparisons were made. As you can see, the standard bind-off is not completely without stretch: the bind-off edge measures 11.5 cm relaxed and 16 cm stretched, a stretch percentage of 39%.
#11. Suspended Bind-off
In the book Cast On, Bind Off: 54 Step-by-Step Methods, author Leslie Ann Bestor suggests that this is a good bind-off for knitters who have a hard time binding off loosely. Turns out this is not the case. The Suspended Bind-off doesn't have any more stretch (nor flare) compared to the standard bind-off.
#10. Lucy Neatby's Modified Conventional Bind-off
Not much improvement with this method: the Modified Conventional Bind-off has a stretch percentage of 52% with 4% more flare compared to the standard bind-off.
#9. Lace Bind-off
The Lace Bind-off performs only a little better: a 57% stretch percentage. It also produces a minimal amount of flare (4%).
#8. Icelandic Bind-off
Now we're starting to see some improvement. The Icelandic Bind-off has a 65% stretchiness with only 9% more flare than the standard bind-off. But because this bind-off methods gives a bumpy edge, it's not ideal for all projects.
Bumpy edge produced by the Icelandic Bind-off.
#7. Standard Bind-off with Larger Needles
All other bind-off tests were done using the same needles but for this method I went up two needle sizes (1 mm). I've always put down using larger needles to bind-off your work as a lazy method that just makes looser stitches with not much stretch. How very wrong I was! This simple trick actually produces quite a good stretch (65%) but only minimal flare (4%) compared to the standard bind-off.
#6. Lori's Twisty Bind-off
Lori titles her tutorial video "Extra Stretchy, No Flare Bind Off" and she is exactly right! This bind-off has a considerable amount of stretch (70%) with absolutely no flare compared to the standard bind-off.
#5. Elastic Bind-off
My favorite bind-off for toe-up socks, Elastic Bind-off, shows up at the middle of the pack. It has a generous amount of stretch (91%) but also quite a bit of extra flare (13%).
#4. Simple Stretchy Bind-off
The Simple Stretchy Bind-off is exactly same as the elastic bind-off, only worked in pattern (that is, knitting the knit stitches and purling the purls). And it stretches even more: a 100% stretch percentage means the bind-off edge stretches to double the width of the swatch. This bind also has the same amount of extra flare as the elastic bind-off (13%).
#3. Jeny's Surprisingly Stretchy Bind-off
Now we're getting into Top 3! The third stretchiest bind-off is Jeny's Surprisingly Stretchy Bind-off with a generous 109% stretch percentage but only 13% more flare. Definitely a good one to use for those sock cuffs.
#2. Elizabeth Zimmerman's Sewn Bind-off
The second best: Elizabeth Zimmerman's Sewn Bind-off. It gives the same amount of stretch as JSSBO but only a measly 4% more flare. Stretchy and attractive!
#1. Yarnover Bind-off
And the number one spot goes to Yarnover Bind-off. This bind-off method produces a whopping 126% of stretch, meaning the bind-off edge can be extended to more than 2.25 times the width of the original swatch. But using this bind-off comes with a caveat. The Yarnover Bind-off also performs the worst in terms of flare: 22% more than the standard bind-off.
So what do these results mean? What is the best stretchy bind-off? It depends on what you're knitting. Here are my suggestions.
The Ultimate Stretchy Bind-off: Yarnover Bind-off. Use this one when your finished project must be stretched and blocked aggressively, such as for lace shawls.
Best Bind-off for Toe-up Socks: EZ Sewn Bind-off or JSSBO. Both are very stretchy but with a bit of flare.
Good All-rounder: Lori's Twisty Bind-off. Not quite as stretchy as the top alternatives but it's pretty. Great for sleeve cuffs and hems where you don't want any flare on the finished object.
For those interested in math and methodology, here's how I calculated the stretch and flare percentages.
I used the same swatch throughout the tests, changing only the bind-off row. I measured the bind-off edge relaxed (unstretched) for the flare percentages and stretched as far as the swatch would go for the stretch percentages.
Standard bind-off was used as a baseline against all comparisons. To calculate the percentages, I used these formulas:
Stretch % = (comparison bind-off edge stretched - standard bind-off edge relaxed) / standard bind-off edge relaxed × 100%
Flare % = (comparison bind-off edge relaxed - standard bind-off edge relaxed) / standard bind-off edge relaxed × 100%
For instance the measurements for Jeny's Surprisingly Stretchy Bind-off were 13 cm relaxed, 24 cm stretched. This yields the following stretch and flare percentages:
Stretch % for JSSBO = (24 - 11.5) / 11.5 × 100% ≈ 109%
Flare % for JSSBO = (13 - 11.5) / 11.5 × 100% ≈ 13%
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