Key Takeaways:
- Your Size Is Not Static: Bra size can shift throughout pregnancy, postpartum, and nursing, which is why measuring regularly makes a real difference in day-to-day comfort.
- Measuring At Home Is Simpler Than It Sounds: A soft tape measure and a few minutes are all it takes to find an accurate starting point for your band and cup size.
- The Right Fit Changes Everything: A well-fitting nursing or pumping bra supports your comfort and your routine from pregnancy to postpartum and beyond.
If you have ever spent most of a day readjusting bra straps or pulling at cups that will not stay put, you already know how much a poor fit affects your comfort. During pregnancy and the postpartum season, your body is changing quickly, your needs shift with it, and knowing how to find your bra size can make a meaningful difference in how you feel each day.
At Simple Wishes, we are a women-owned brand founded by sisters Debra and Joy to make nursing and pumping more manageable for every mom, from pregnancy to postpartum and beyond.
In this piece, we cover how to measure your bra size at home, how fit changes through pregnancy and nursing, and what to look for in a bra built for this season.
Why Bra Fit Matters More During Pregnancy And Postpartum
Breast tissue changes significantly during pregnancy and the postpartum period, and these changes do not always happen on a predictable schedule. A bra that fits too tightly can put pressure on breast tissue, while one that fits too loosely provides little real support. For nursing moms, a poor fit may also contribute to discomfort during or between feedings.
Understanding how to find out your bra size, and doing it more frequently than you used to, is one of the small practical habits that can improve your everyday experience during this season.
How To Find Your Bra Size At Home
Knowing how to find your bra size at home means you can check your fit any time rather than waiting for a fitting appointment. All you need is a soft tape measure and a few minutes.
Measuring Your Band Size
Wearing an unpadded bra, wrap the tape measure snugly around your ribcage, directly under your bust. Keep it level all the way around and firm against your skin without digging in — we recommend tightening on the exhale and noting the smallest measurement to the decimal, in inches.
Here's the part that trips a lot of moms up: that underbust number isn't your band size. At Simple Wishes, your band size runs larger than your raw measurement — anywhere from 1" to 4" more, depending on where you fall. For example, if you measure between 29.5" and 31.4", you're a 34" band in Simple Wishes sizing.
For your exact band size (and full cup size, in one go), use the calculator on our Measuring Guide, or check the complete size chart at the bottom of that page.
How To Find Your Bra Cup Size
Next, wrap the tape measure around the fullest part of your bust, keeping it parallel to the floor. Relax your shoulders, and round up to the nearest whole number.
Now here's the step where a lot of moms get tripped up: subtract your Simple Wishes band size — not your raw underbust measurement — from this number. Remember, your band size typically runs 1"–4" larger than what you measured under your bust, so using the wrong number here throws off your cup size too.
The difference corresponds to your cup size: a one-inch difference is approximately an A cup, two inches is a B, three is a C, and four is a D, with each additional inch adding another cup size from there.
How To Find Your Bra Size With A Tape Measure: A Few Practical Notes
Accuracy improves when you measure over a non-padded or lightly lined bra — one that puts your breasts in the position you want them to sit in day-to-day, rather than measuring bare. Taking each measurement twice helps confirm a consistent reading, and keep in mind that sizing can vary between brands and styles.
How Your Size Shifts Through Pregnancy And Nursing
Most moms find that their bra size changes at least once during pregnancy, often again when milk comes in postpartum, and sometimes again as supply regulates. Moving through two or three different sizes during this period is entirely normal — which is why the right bra shouldn't have to be reset every time your body shifts.
Look for a bra with a 2" band extender, which makes it easier to transition sizes between late pregnancy and early postpartum without buying a whole new size. In that early postpartum window, a soft, flexible cup is your best friend — the SuperMom® Silhouette with removable pads flexes with you as things change day to day.
Once your milk supply has established and your size has stabilized, switch to the fixed-pad version of the Silhouette. It creates a smooth shape and separation between breasts, giving you the closest feel to a normal, wire-free T-shirt bra — ideal for heading back to work.
If you are nursing or pumping, breast tissue can also fluctuate throughout the day depending on when you last fed or pumped. This natural variability is part of why flexibility in fit matters as much as your measurements during this season.
What The Right Fit Actually Feels Like
A properly fitting nursing bra should feel supportive without being restrictive. The band should sit level and stay in place without riding up, the cups should contain breast tissue fully without gaping or spilling at the sides, and straps should stay comfortable without digging in.
For nursing and pumping specifically, practical access matters too. A clasp or opening you can manage with one hand makes a genuine difference during nighttime feedings or when nursing in a busy moment.
Bras Built For This Season
Finding a bra that fits well matters, and finding one built for the demands of nursing and pumping matters just as much. Our maternity nursing bras are crafted from buttery-soft, OEKO-TEX certified fabrics with heat-seal labels and minimal seams to reduce irritation against sensitive skin.
For moms who pump regularly, our nursing and pumping bra options allow you to nurse and pump without changing, saving real time across your day. Our pumping sports bras offer the same hands-free functionality in a more flexible, active fit. Our nursing tops give you easy access for feeding while keeping you comfortable and put-together, and our nursing jumpsuits are an easy reach for home days and outings alike, with no layering required.
Our award-winning SuperMom® Silhouette features a unique clasp that drops both layers for breastfeeding, along with both fixed and removable padding options so you can find what works best throughout your journey.
Final Thoughts
Finding the right bra fit is one of those things that is easy to overlook until it is affecting your entire day. During pregnancy, postpartum, and the nursing season, the right fit can support your comfort, your confidence, and your routine in ways that add up. We built Simple Wishes because every mom deserves thoughtful essentials that make this season feel a little more manageable.
Frequently Asked Questions About Our Bra Fitting Sizes
How often should I measure my bra size during pregnancy?
Measuring every four to six weeks during pregnancy can help you stay ahead of changes. Many moms go up one or more band and cup sizes between early pregnancy and delivery.
Does bra size continue to change after delivery?
Yes, size often changes again in the early postpartum days when milk comes in, and may shift again as supply regulates. Remeasuring every few weeks during the early postpartum period can help you find a consistent fit.
What is the most accurate way to measure my bra size at home?
Using a soft tape measure to measure your band directly under your bust and your cup at the fullest part of your breast gives the most reliable starting point. Taking each measurement twice improves accuracy.
If you're pregnant and your ribcage has already started to expand, here's a helpful double-check: measure around your ribcage directly under your armpits. No extra math needed — just round that number up to the next even number, and that's your Simple Wishes band size for postpartum.
Can bra fit affect nursing comfort?
A bra that fits too tightly may put pressure on breast tissue, which can contribute to discomfort during or between feedings, as well as clogged ducts and mastitis. A well-fitting nursing bra that allows easy access and does not constrict can make a real difference in your nursing experience.
Does breast tissue change throughout the day while nursing?
Yes, breast fullness can vary depending on how recently you have nursed or pumped. A bra with some flexibility in the cups can help accommodate these natural shifts more comfortably throughout the day.
What should I look for in a postpartum nursing bra besides fit?
Soft fabrics that minimize irritation, easy one-handed access, and a design that works for both nursing and pumping can all contribute to a more comfortable day. Front-adjustable straps, multiple hook-and-eye positions, and a 2" band extender offer more flexibility as your body continues to change.
Can I wear the same bra for nursing and pumping?
A nursing and pumping bra is designed to handle both functions in one piece, so you do not need to change between feedings and pumping sessions, which can meaningfully simplify your routine.
Disclaimer: This content is not intended to be a substitute for professional medical advice or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
Sources:
- Assessment of breast volume changes during human pregnancy using a three-dimensional surface assessment technique in the prospective CGATE study - https://pubmed.ncbi.nlm.nih.gov/24100511/
- Maternity bra fitting during pregnancy and postpartum: Advice from experts — Mother & Baby - https://www.motherandbaby.com/mum/postpartum/bra-fitting-during-pregnancy-and-postpartum/
