Wear a non-padded bra and use a soft tape measure. Hold the tape measure around your back at band level. Then bring it to the front, just above your bust.
The resulting number is your band size.
Hint: If the number is odd, round down to the closest even number.
Thread tape measure under your arms, across shoulder blades at back and around fullest part of bust at front. Relax arms at sides while keeping tape parallel with the floor. This is your bust measurement. If this measurement falls on the 1/2 inch, round up to the next number.
Subtract the band size (Step 1)
from the bust measurement (Step 2).
This number equates to the letter of your cup size.
Bust Measurement - Band Size = Cup Size.
For example, if your bust measurement is 36" and your band size is 34, you wear a B Cup.
Stand on a level surface with feet together. Measure around fullest part of hips and bottom (approximately 7"-9" below waist-line), keeping tape parallel to the floor.
Thread tape measure under your arms, across shoulder blades at back and around fullest part of bust at front. Relax arms at sides while keeping tape parallel with the floor. This is your bust measurement. If this measurement falls on the 1/2 inch, round up to the next number.
Bend to one side to find natural indentation in torso. This is your natural waist. Run tape around natural waist-line, keeping tape parallel with floor and one finger between body and tape for a more comfortable fit.
Stand on a level surface with feet together. Measure around fullest part of hips and bottom (approximately 7"-9" below waist-line), keeping tape parallel to the floor.