Test Bra Band Elastic Before You Sew

Test Bra Band Elastic Before You Sew

Before you cut fabric, before you thread the machine, before you wonder why this bra feels different from the last one — there’s one small step that saves time, frustration, and unpicking:

Test your bra band elastic before you sew.

It takes less than five minutes to test bra band elastic, requires no special tools, and gives you information you can use every single time you sew a bra. Your Fairy Bra Mother highly recommends it.

In my last post, and the one before that, I showed you how to measure for elastic stretch, and how to adjust the pattern. This post is all about never having another elastic disaster.

What You Need (Nothing Fancy)

• A ruler or measuring tape
• A pen and scrap of paper (or a notebook you won’t lose)
• A short length of bra band elastic

That’s it. No spreadsheets required… unless you enjoy them.

Step 1: Measure Elastic Stretch Percentage

Cut a 10 cm (4 inch) length of elastic. if you prefer, you can use 10″ (25 cm) of elastic.

1. Measure the elastic with no tension
2. Stretch it until it feels firm but your fingers meet resistance
3. Measure the stretched length

Calculate Stretch Percentage

(Stretched length - relaxed length) ÷ relaxed length × 100

Example

• Relaxed: 4″ (10 cm)
• Stretched: 6″ (15 cm)

That elastic has 50% stretch.

Write this number down. You will use it.

Step 2: Do a Quick Recovery Test

Stretch the elastic firmly and hold it for a few seconds. Then release.

Ask yourself:

• Does it return immediately?
• Does it look longer or slightly wavy?
• Does it feel tired already?

Elastic with poor recovery may feel fine at first but often leads to bands that loosen quickly during wear.

Stretch is enthusiastic. Recovery is commitment. You want both.

Step 3: Assess the “Feel”

This part is subjective – and that’s okay.

Gently stretch the elastic between your hands and notice:

• Is it soft or firm?
• Does it resist stretch smoothly or suddenly?
• Does it feel supportive or flimsy?

Two elastics can have the same stretch percentage and still feel different. Your hands will learn to recognize this faster than you think.

Step 4: Decide How to Use This Elastic

Based on what you’ve learned:

• Under 40% stretch:
  Firm – likely needs a slightly longer band
• 40–50% stretch:
  Medium – works well with most drafted patterns
• Over 50% stretch:
  Soft – often needs a shorter band for support

This is where my last post and the one before that come into play. Testing tells you what you’re working with; adjustment tells you what to do about it.

Step 5: Label or Record the Information

Future-you will be grateful.

At a minimum, record:

• Stretch percentage
• Source or brand (if known)
• Your impression (firm, soft, great recovery, questionable life choices)

You can:

• Keep a small elastic log (in my next post, I have prepared an elastic testing worksheet)
• Tape a note to the elastic card
• Write directly on the packaging

Whatever you’ll actually do consistently is the right system.

Step 6: When to Reject an Elastic

Not all elastics deserve to become bras.

Consider setting an elastic aside if:

• Recovery is poor
• Stretch feels uneven or jerky
• It doesn’t return to length after testing

There are many lovely elastics in the world. You do not need to force a relationship with a bad one. And sadly, elastics with rubber (latex) in them have a limited shelf life. They will stretch and never recover. They are well and truly dead.

Why This Tiny Habit Matters

When you test bra band elastic, you:

• Improve fit consistency
• Reduce wasted time and fabric
• Make pattern results predictable
• Build confidence in yourself quickly

Most importantly, it moves you from hoping a bra will fit to knowing why it will.

And you, dear sewist, are on your way to becoming a bra engineer!

If elastic behavior still feels mysterious, start with my first post on understanding bra band elastic stretch and recovery

If you haven’t seen my little bra elastic video, click here.