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Finding the Right Fit for Your Bicep

Posted by Betsy C on

Tis the time of the year where fear of setting in sleeves must be put to the side as sleeveless is just not an option for the cold weather. But to make sure your sleeve setting efforts are worth it, I would like to share some tips on checking to see if your bicep width will work out for the fit you are going for. 

The number will vary based on fabrication: 

For a super stretchy knit fabric, you may prefer a tighter fit in the bicep. This is ok, because a knit can easily accommodate a greater variance in bicep width. However, for a woven fabrication, that has no give, the number must be, bigger.

Here a two examples that fit the same arm. 

To start, grab your best fitting biceps from your closet: 

This can be a garment that you made that you are happy about the bicep fit, or it can be a a ready to wear item. The point is find something that you know fits well, and we will base your bicep on this. But as per above, please make sure the fabric is same/similar to get the right numbers.

Grab a tape measure: 

Align your sleeve, so it is folded in half. Measure 1" below the armhole seam, perpendicular to the folded edge (parallel to sleeve opening). Take this measurement and multiply be two and you have your bicep measurement! 

Measure your pattern: 

Mark your seam allowance widths. 

 Starting from 1" at the underarm, at the seam allowance mark (sew line), measure straight across from seam to seam. 

What the numbers mean: 

So your garment muscle is 13 1/2". Your pattern measurement is 12". This means that you will need to add 1 1/2" total to the bicep width. 

Next post, I will show you the best way to increase and decrease and explain the implications involved in making these changes. It's gonna be a hefty one so stay tuned! 


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  • @ mükikoo Be sure to check out my follow up post to this at

    betsy on
  • Ahem…grab your best fitting biceps from your closet
    Isnt using the solution to fix the problem ?
    If you have a problem withthe fit of biceps, it likely that your garments dont fit in this area.

    mükikoo on
  • Hi Pauline,
    Don’t worry, you didn’t miss anything. I am completely delayed on getting this up. Admittedly it’s one of those projects I lost momentum on and now I have to pick it up again- My version of a “UFO”. It’s a biggie, so I need to really pull a lot of stuff together. But rest assured, I have not totally forgotten!

    Betsy on
  • I came to SBCC patterns today and purchased one. I came looking for information about altering the biceps area and found this post, a further one is promised, but doesn’t seem to be here. Am I looking in the wrong place. A link please?

    Pauline on

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