how to do a full bicep adjustment

HelenBlackwood Cardigan, Blackwood Sewalong, Fitting & Pattern Adjustments43 Comments

How to do a full bicep adjustment

how to do a full bicep adjustment

Today is the third installment in the Blackwood Cardigan Sewalong! In case you missed the first few posts, we have covered how to grade between sizes, how to do a quick ‘cheater’ full bust adjustment, and how to do a ‘full’ full bust adjustment, both on a bodice without any darts. Now, we are going to cover how to adjust the width of the sleeve for larger arms. This is called a full bicep adjustment.

The Blackwood Cardigan has slim sleeves designed for layering under jackets and giving a nice, close fit. Because the pattern is designed for fabrics with plenty of stretch, most people will be fine with the sleeve as-is. That said, some of you may wish to get more room for layering over long sleeve shirts or want to add width if sleeves typically fit too tight on you.

Blackwood Cardigan PDF Sewing Pattern

This post is part of a sewalong for the Blackwood Cardigan. You can grab your copy of the Blackwood here.

Do you need a full bicep adjustment? First, you need to measure the circumference of your arm at the widest point. This is usually at the bicep.

full bicep adjustment

Next, measure your pattern piece at the widest part. Decide how much ease (extra fabric) you want in your sleeve. Knit patterns often have negative ease, or just a little bit of ease. The Blackwood Cardigan is designed with 1/2″ of ease. Fitted woven sleeves typically have 1-3″ of ease.

full bicep adjustment

Your bicep measurement – the sleeve measurement + the amount of ease you want = your adjustment amount

For example. Let’s say my bicep measures 14″. My sleeve measures 14″ across (not counting the seam allowance). I want an ease of 1″, so my calculation is 14-14+1=1″.

Now that we know how much we need to adjust for, we can get started!

I like to trace my pattern piece onto a new piece of paper or print out a second one. If you are adding more than 1″, you will need your original pattern piece later.

full bicep adjustment

Next, draw a line from the middle of the sleeve cap to the bottom of the sleeve, parallel to the grainline. Draw a second line perpendicular to the first at the widest part of the sleeve.

full bicep adjustment

Now, cut these lines, leaving a little bit of paper right at the seam allowance. Clip into the seam allowance, too, so we can pivot the paper easily.

full bicep adjustment

Anchor the bottom of the sleeve with your finger or a tack. Push the top of the sleeve down and the sides out. Your pattern will start to overlap in the middle and a gap will form.

full bicep adjustment

Keep moving the pieces until your gap is as wide as your adjustment amount.

full bicep adjustment

Fill in the new space with paper, leaving excess paper at the top and bottom of the sleeve for the next steps.

full bicep adjustment

Now, things diverge a bit here. If you have added up to 1″ to your sleeve, you can simply smooth out the sleeve cap and bottom edge and be on your way. The height of the sleeve cap hasn’t changed so drastically that we need to redraw it, especially if you are working with a knit. If you have added more than 1″ to your sleeve, you will need to re-draw your sleeve cap and adjust the bodice pieces.

For those of you who added up to 1″

Smooth out the sleeve cap by drawing a new curve at the top.

full bicep adjustment

Straighten out the bottom edge by drawing a straight line.

full bicep adjustment

Cut off the excess paper and you are good to go!

full bicep adjustment

For those of you adding more than 1″ 

You will notice that your sleeve cap is quite distorted and short looking if you make a big adjustment. We need to get the nice curve it had to begin with back.

full bicep adjustment

Using the original pattern piece as a guide, trace the original sleeve cap curve and straighten out the bottom edge.

full bicep adjustment

Now, trim off the excess paper and we have our new sleeve! But wait, there’s more. We also need to change the bodice to accommodate the extra fabric in the new sleeve cap, otherwise, you will have a hard time easing all that extra fabric into your shoulder seam. You have two options here.

1. You can deepen the arm hole by half of the amount you added to your sleeve.

full bicep adjustment

2. You can add width to the side seam by half of the amount you added to your sleeve.

full bicep adjustment

Lastly, you could do a combination of both!

I hope this post on how to do a full bicep adjustment has been helpful! I urge you to try one if you are bothered by tight sleeves on a regular basis. The adjustment is fairly simple and it can make a big difference.

Tomorrow I am going to share how to do a narrow or broad shoulder adjustment. I hope you check it out.

Do you have a different method for making a full bicep adjustment? I’d love to hear about it!

About the author


Helen Wilkinson is the designer and founder of Helen's Closet Patterns. She also co-hosts the Love to Sew Podcast! Helen is obsessed with all things sewing and strives to share her passion and knowledge with the sewing community.

43 Comments on “How to do a full bicep adjustment”

  1. Thank you so much for these clear instructions I have been looking for a while and have found partial instructions but none as detailed or clear as yours.

  2. Thank you so much for your clear, easy to follow instructions. I am a breast cancer survivor, and, as a result of treatment, have been left with very large upper arms – lymphodema. I need to add two inches to my bicep and have struggled with this for years. Wish I had found your article years ago.

  3. This has been so helpful to me. Thank you! I always need to adjust everything. This is better than the system I came up with. Thanks so much for sharing your knowledge

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  5. Hi Helen, this is very helpful! But when you said the options for 1 and 2 above, does that mean to add to the front and back bodice pattern?

  6. I have a problem with this type of bicep adjustment- it adds width to the sleeve above the arm pit area, and makes this area too baggy and I get drag lines- I guess all my extra width is in the bicep directly under the arm and my upper arm and shoulder do not need the extra room- – how do I adjust the pattern to give me room wHere I need and not add room I don’t need in the very top of the sleeve?

    1. Hi Faye, great question! You can move the crosshairs down and cut the sleeve open at a lower position. Then you can sew the arm seam with a bit of a curve in it, making more room at the lower bicep or further down the arm as needed.

  7. Hi. I love your post here. But from what i see, you are keeping the sleeve cap the same by adjusting the inside. Therefore, shouldn’t the original armhole stay the same?

    1. Hi Sharon! For the first method shown here, we are not changing the sleeve cap and therefore do not need to add to the bodice, but for the second method, we are changeing the sleeve cap and need to do the same to the bodice. Thanks!

  8. Thankyou Helen, I have struggled for years with sleeves being too tight on my home seen garments & your explanation of dealing with it was so simple to follow

  9. Thanks! This is a struggle for me!! Can’t wait to try it. Could you point me to a resource that shows you how to do this for a dolman type drop sleeve??
    Thank You!

  10. Thank you so much for this tutorial! I’ve just used it to alter my Gilbert sleeves. So many other tutorials tell you that you need to adjust the armscye if you do a large adjustment, but don’t actually SHOW you how to do that. Your tutorial was a godsend. So very beginner friendly and doesn’t assume any prior knowledge. THANK YOU.

    1. That means so much, thank you for your kind words! I’m so happy to hear you found our post helpful and informative. :)

  11. Thank you so much, my bicep issue is in the larger part of the bicep so if I move the cross part down it will still be ok? I have to widen 2 inches, and I see where I have to adjust the sides by 1/2 inch correct?

    1. Hi Debbie! I would recomment making two crosses in this case – one at the armpit and one further down. Then, you can widen the sleeve in both spots. The finished sleeve will have a rounded shape to it because of the extra fabric added in the mid-upper arm. I hope that helps!

    2. Hi Debbie! I would recommend making two crosses in this case – one at the armpit and one further down. Then, you can widen the sleeve in both spots. The finished sleeve will have a rounded shape to it because of the extra fabric added in the mid-upper arm. I hope that helps!

  12. Thank you soooo much for writing this (and your comment to Debbie above, which is also my problem)! I started weightlifting two years ago and my biceps have started to go crazy in the past six months. A lot of my woven me-mades don’t fit my arms anymore :( Thank you, I can now make some new me-mades!

    1. Hi Sarah! Congrats on the new super-strength!! I’ve been weightlifting for a year or so now and it is really fun to watch the muscles grow, isn’t it!? I’m glad you found this helpful. Happy sewing.

  13. Thank you SO much for this! I have some glorious material to make a top but have ham-hocks for biceps, so haven’t cut it. I’ll be doing that this weekend!

  14. Like so many others – brilliant explanation. I have been looking online for some time and had many failures. Not this time! And thanks for including instructions for woven fabric as well as knits.

  15. Thank you so much for this full bicep adjustment. For many years, I have been trying to figure out how to make this adjustment.

  16. Thank you so much…your post with these clear instructions make my day. I’ve been struggling with the type of adjustment forever
    By the time I drop the bust point by 3” then accommodate my narrow shoulders the 2extra inches needed for bicep seems impossible. I’m trying this out on the weekend

    You are a genius

  17. Thank you for this tutorial! Do you have a tutorial for a 2 part sleeve adjustment? I think it must basically be the same, but I’m having trouble wrapping my head around where to draw my adjustment lines. Thanks for any guidance.

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