Calculating Bra Under Band Length Posted on 24 May 15:43 , 0 comments

Wondering how to adjust your under band pattern pieces to get the perfect fit? Well, today’s quick tip is for you.

New blog post reviewing these two ladies coming soon.

Take your underbust measurement and calculate 10-15% of this measurement. What % you choose will depend on how firm your Powernet is and how tight you like the band. I prefer to subtract the whole 15%. Subtract this from your underbust measurement. You then must also subtract 2″/5cm for the hook and eye. However, if you are making a front closure bra you would subtract only the width of that closure.

Example for a 36 band with an actual underbust measurement of 32″

32″/ 81.2cm x 0.15 = 4.8″ / 12.18cm

32″/ 81.2cm – 4.8″ / 12.18cm = 27.2″ / 69.02cm

27.2″ / 69.02cm – 2″ / 5cm = 25.2″ / 64.02cm

Once you have calculated the finished length of your under band you need to compare it to your flat pattern. Since most patterns only cover half the bra you may want to divide this value by two. In my case that would be 12.6″ or 34.5cm. How this value gets distributed between the frame and band will depend on your pattern. You could take a second measurement across the front only from where you would like your side seams to be placed and use this to adjust the frame.

This is only a basic formula based on my education and experience in bra pattern making. Your results may vary but it’s a good method to use to avoid having to make random adjustments. This is an adjustment you could make to your pattern before the first fitting.

Hope this helps.

  • The simplified formula for this is 0.85x – 5cm with x = your underbust measurement. This is when you’re subtracting 15% for negative ease only.