You aren't alone if you don't already know your bra size. So, how do you choose the best size for you before you dive into sewing your own bra? I always recommend starting with your ready to wear size but if you don't know what that is, or if you know that your current bra isn't fitting well, then this is an easy way to calculate your size & usually offers a good jumping off point. It's worth bearing in mind that sizing varies from brand to brand as does body shape from person to person so it's likely you'll need to make some tweaks to any sewing pattern before you achieve that perfect fit. That's why I always recommend making a toile or a test garment before you cut out your final fabrics. Read on to dicover how to easily calculate your bra size...all you need is a tape measure.
1. The first step is to determine your underband. Do this by wrapping a measurement tape snugly around your torso, just under your bust & note down the measurement in inches (round to the nearest whole number).
Did you know that most people are surprised to learn that they would benefit from a tighter underband? It should be very snug so if you're between numbers I recommend rounding down.
2. Now, wearing an unpadded bra, measure around the fullest part of your bust, ensuring the tape measure isn't too tight. Take a breath or two and make sure the tape measure feels comfortable and non-restricted before noting the nearest whole number.
3. You can now determine your cup size number which will correlate to your cup letter. Your cup size number is your bust measurement minus your underband measurement.
For example, my underband is 36" and my bust measurement is 41". My cup size number = bust (41) - underband (36) = 5
By referring to the chart below I can see that my cup letter is DD. So my bra size is 36DD which coincidentally is the UK's average bra size!
I hope you found this guide helpful. Let me know in the comments if you're new to bra making or if you're in the process of perfecting your fit. While you're here why not browse my selection of lingerie sewing patterns?