Find the Best Possible Bra Size

When you are going to make your own bra, it’s extremely important to find a right cup size first. The fit of the bra band can easily be adjusted when trying the bra on.
bra size labels

There are two-three approaches to choosing the size – with the help of the following facts:

The size of your current well fitting bra = your ready-to-wear bra size
Your under and full bust measurements (how to measure?)

Let’s take a closer look how to choose the bra pattern size by those facts.

1. By Your Current Bra Size

You may get close to the right cup fit by choosing the size based on your current ready-to-wear bra size.

The problem may arise from the unrealistic under bust measurement of them, which quite often is at least 5-15cm smaller than your actual measurement is. That means the cup size is larger (i.e. the letter goes up).

Compare your own under bust measurement to your ready-to-wear bra band size. Typically the difference will grow at the ends of the size range. Rarely a women with the underbust 100cm (44) finds a bra in that size, instead it may be 85-90 (38-40).

Pros and cons of the method
+ The cup size may fit perfectly (depends also on the model!)
The band length of the pattern may be too short. However, lengthening the band is very easy.

2. By the Measurements

Take your under and full bust measurement wearing a non padded bra. The two measurements you get are proportioned to each other and make up your bra size. However, only a woman whose breasts take a certain proportion of the full bust measurement in relation to the back can find her size by the chart because it is made for the average.

If the cup size given by the chart differs from the cup size you are usually wearing, take a look at the options below.

BRA SIZE CHART CMS (klick to open)


BRA SIZE CHART INCHES (klick to open)


You can also calculate the size of a cup by simple subtraction: full bust – underbust. The difference shows the cup size letter.

13 15 17 19 21 23 25 27 29 31
Important Sizing Tip

The cup size depends strongly on the relation between the back width and the full bust measurement. Ladies in the picture need different sized cups despite having exactly the same under and full bust measurements.


  • Lady Blue has narrow back and fuller breasts. She needs one or even two sizes larger cup than the chart tells her.
  • Lady Green is the lucky one and finds her size from the size chart.
  • Lady Red has rather broad back and smaller breasts. She needs one or even two sizes smaller cup.
fr Un conseil important sur les tailles
DE Wichtiger Hinweis für die Abmessung


Pros and cons of the method
+ Easy to find the size if you are an ”average” woman
The margin of error increases when the width of the back becomes bigger or smaller

3. By the Mix of Your Measurements and Your Current Bra Size

Maybe the best approach would be to compare the size given by the measurements and your ready-to-wear bra size. If they don’t match, do like this:

1. Take your real underbust measurement as a fact. Round it up or down as in the table below.

Measurement > SIZE
68 – 72cm > 70
73 – 77cm > 75
78 – 82cm > 80
83 – 87cm > 85
88 – 92cm > 90
93 – 97cm > 95
98 – 102cm > 100

2. Convert your ready-to-wear bra size to match your real bra band measurement with the help of the sister size chart. Parallel sizes are on the columns. Sister sizes refers to the bra sizes that have the same cup volume although the band size changes.

Example: Your underbust measurement is 95cm and the size of your ready-to-wear bra is 85G. Adapt the size 85G into a 95 series. The result is 95DD.

Sister Sizes
Band size Cup size
60 (28) C D DD F G H I J
65 (30) B C D DD F G H I J
70 (32) A B C D DD F G H I J
75 (34) AA A B C D DD F G H I J K
80 (36) AA A B C D DD F G H I J
85 (38) AA A B C D DD F G H I
90 (40) AA A B C D DD F G H
95 (42) AA A B C D DD F G
100 (44) A B C D DD F
105 (46) A B C D DD
110 (48) A B C D
Pros and cons of the method
+ Probably less pattern adjustments
Requires mathematical pondering

How To Measure

bra measurements

Under Bust

Place the measuring tape firmly on the lower edge of the bra, parallel to the floor. Keep the tape snug. Compare your under bust measurement to the size chart below.

Full Bust

Measure around your body at the fullest part of your bust keeping the measuring tape in place firmly, but softly. The tape should stay parallel to the floor.
Now you have two figures that lead you to your bra size. Find your full bust measurement from the middle of the number pairs at the row corresponding to your band size. The letter above is your cup size.

Other Underwear Measurements cms

For underpants you will need two measurements: the waist and hip measurement. The hip measurement is the most important and the pattern of the panties should be selected on the basis of it. Hip measurement is taken from the widest part of the hip by pulling the measuring tape snug, but not too tight.

Chest 80-84 88-92 96-100 104-110
Waist 64-68 72-76 80-84 88-92
Hip 88-92 96-100 104-108 112-118