Let’s find your Bra Size Starting Points!

This guide will show you a simple way to calculate your bra size starting points. I say “starting points” because your bust and underbust measurements will give you an approximate idea of your current bra size. Numbers are information, not a definition. And because every bra fits differently, women’s bodies fluctuate, and brands size their bras using various methods, there is no one standard or scientific way to calculate your exact bra size.

My hope is that by measuring yourself and calculating your bra size starting points, you’ll be one step closer to saying hurray! Use these starting points to make an informed purchase online, to choose bras to try on at your local shop, or even to stay in the know when working with a bra fitter.

After using the simple guide below, I’ve shared a few of my favorite resources for you to use these bra size starting points. From a guide on how to tell if your bra fits, to learning how bra sizing works across the globe. PS: Check out the More Than My Numbers project to see what bra sizes other women wear!

Are you ready to find your bra size starting points?

Let’s Do This!

What you will need: A soft measuring tape (you can get one at a drug store or sewing supply shop), your best fitting, basic bra (avoid push up or minimizer styles), pen and paper (or somewhere to write your measurements) and an open, loving heart.

Step 1: Measure Your Bust

Measure Your Bust

  • Bring the measuring tape around your torso where your bust is the fullest.
  • Keep it straight, and level with the floor.
  • Do not squeeze too tight or keep it too loose. Keep the tape nice and taught.
  • Record your measurement in inches, rounding to the nearest half inch.

Ex: A woman’s bust measures 33″

Step 2: Measure Your Underbust

Measure Your Underbust

  • Bring the measuring tape around your torso just underneath your bust.
  • Keep it straight, and level with the floor.
  • Do not squeeze too tight or keep it too loose. Keep the tape nice and taught.
  • Record your measurement in inches, rounding to the nearest half inch.

Ex: A woman’s underbust measures 29″

Step 3: Find Your Starting Points

Find Your Starting Points

  • US band sizes run in even sizes. Using your Underbust measurement, add 0 inches to 1 inch to get the closest even number. Ex: If a woman’s Underbust is 29″, an odd number, she would add 1 inch to get 30.
  • Next, subtract that number from your Bust measurement to get your cup size calculation. Ex: A woman’s Bust measurement is 33″. 33-30 = 3
  • Using the English alphabet, find your cup size, using each letter for a number. 1 = A, 2 = B, etc. Ex: A woman’s cup size calculation is 3, so 1(A), 2(B), 3(C).

Ex: Her first bra size starting point is 30C.

  • Next, find your second starting point size (or your “sister size“) by going up one band size, and down one cup size. Ex: A woman’s bra size 30C. Her second size is one band size up, 32, and one cup size down, B.

Ex: That means her second bra size starting point is 32B.


You’ve got your bra size starting points. Now what?

Use these resources to say hurray for lingerie

Free Bra Class

Want to wear a bra without ripping it off at the end of the day? Watch How to Find a Comfortable Bra Fit For Your Body WITHOUT Wasting Your Money on Bras You Dread Wearing! Plus, you'll also get Kimmay's Bra Fit Guide, and a taste of Bra Confidence & Comfort™. Watch now and don't spend another minute feeling uncomfortable in your bra.

Top 5 Bra Fit Tips Video and Guide

Download my video and PDF guide and learn how to tell if your bra fits! Use this guide when deciding between sizes, trying on bras at home, or while out shopping.

Sister Sizing

Learn what “sister sizing” is and how it works so you can adjust your bra size and find the best fit for you.

Bra Sizing

Did you know more than one bra size can fit? In fact, 9 fit me! Learn why this is (plus photo examples) and get links to my bra sizing guides and resources.


More Resources

Explore my favorite lingerie and bra fitting resources! From articles, posts, and tools to shopping information and style advice. Everything you need say hurray underneath.


Bra Confidence & Comfort™ helps everyday people find a super comfortable bra fit for their body without wasting money on bras they dread wearing {so they can feel amazing and start each day with a hurray!}