Fitting and Size Guide

Please follow our fitting guide below to determine your bra size. Please bear in mind that your bra size will fluctuate during the stages of your pregnancy and after you have had your baby so we have also given you some fitting advice for each trimester.

A – Around the Bust
B – Around the underband.

To carry out these measurements we recommend that you wear a non padded bra and ensure that the tape is level around your body.

To find your cup size (A) take a relaxed measurement over the fullest part of your bust.

To measure around your underband (B) take a measurement with the tape measure closely around the body.

If you have any questions regarding sizing please get in touch with our team who will be happy to help!

Bra Size Chart in Centimentres

Underbust Measurement (B) 63-72 73-77 78-82 83-87 88-89 88-92
Underband Size 30 32 34 36 38 40

Cup Size (Measurement A)

A 77-79 82-84 87-89 92-94 97-99 102-104
B 79-81 84-86 89-91 94-96 99-100 104-106
C 81-83 86-88 91-93 96-98 101-102 106-108
D 83-85 88-90 93-95 98-100 103-105 108-110
DD 85-87 90-92 95-97 100-102 105-107 110-112
E 87-89 92-94 97-99 102-104 107-109 112-114


We recommend that you fit your bras on the tightest hook at the beginning of your pregnancy so that the bra can be adjusted to bigger sizes as you are growing through your pregnancy and you can get the most wear out your maternity bras. All of our back fastening bras have four rows of hook and eyes to allow you to adjust the underband during the various stages of your pregnancy.

By the time you are ready to give birth you are likely to have you bra adjusted to the loosest hook, you can then begin to tighten the underband after you have given birth.

Please now follow the below chart to find your size in in Six bras – we have tried to make things nice and simple with 3 sizes Small Medium Large. Choose your cup size and underband size, where they meet on the chart is your size in Six.

All of our bras are made in luxury fabric that offer great stretch and support so that they adjust and grow with you during your pregnancy. We recommend buying a size that allows for an increase in your cup size if you are buying early on in your pregnancy.

Six Bra Size Guide

 Underband Size B Cup C Cup D Cup DD Cup E Cup
32 S S S M M
34 S M M L L
36 M M L
38 M L
40 L

Shopping by Trimester

First Trimester 0–3 Months

One of the first signs of pregnancy is an increase in your cup size and also as your ribcage begins to expand your usual bras will begin to feel tight and uncomfortable.

Usually by the end of the first Trimester you will be ready to invest in some maternity underwear. This along with maternity jeans are generally the first essential new additions to a pregnant womans wardrobe.

Second Trimester 3–6 Months

By Six months pregnant there is no hiding the fact that you are officially pregnant!

This is where our brand name comes from as at Six months you are visibly pregnant and need to adapt your wardrobe to accommodate your growing baby.

Your bra size will have increased a full cup size or more by this point, and your underband will also have increased as your bump is growing and your ribcage is expanding.

Third Trimester 6–9 Months

At the end of your third trimester your almost ready to deliver and you may have noticed a further increase in your cup size.

During your third trimester you will be preparing your hospital bag – comfort is key for your underwear choices at this stage as once your baby arrives and your milk comes in your breasts become very full and heavy.

Fourth Trimester 9+ Months / Newborn 0–6 Weeks

Once you have given birth your breast will become significantly bigger and heavier. You will increase at least a cup size as your milk first comes in – this will settle once you have established feeding. During this stage you will feel relief in your rib cage and can begin to tighten the underband on your bra to offer more support.

Established Nursing 6+ Weeks

By this stage you will have established breastfeeding with your baby and by around 10-12 weeks after giving birth your breasts will have decreased in size and weight and you should feel a lot more comfortable.


All of our bras are suitable to wear both during and after pregnancy once you begin feeding your baby.

Six bras offer the functionality of nursing bras with either nursing clips – these are very discreet and sit at the top of the cup/bottom of the strap and are easy to unfasten with one hand. Nursing clips allow the cup to drop down fully for feeding access and they are great for ‘skin to skin’ contact with your baby whilst feeding.

The other feeding option our Florence bra offers is a pull to the side cup – this allows for very easy access to the breast for feeding – perfect for day or night feeds.

Buying a Gift

If you are buying a gift we recommend buying based on someone’s clothes size. If you are inbetween sizes we recommend you choose the size up.

No need to worry about wrapping as all of our products come beautifully wrapped in branded Six wrapping.

All items are exchangeable (excluding knickers for hygiene reasons) so no problem if you buy the wrong size we would be happy to exchange.