When measuring your bust and chest circumference, it's easy to make a lot of mistakes, and then you wonder why your bra doesn't fit after all. It's very important that you place the tape measure horizontally around your body and exhale before measuring so that the shortest measurement is taken. Don't pull the tape measure too tightly around your body; rather, place it loosely. It's best to wear an unpadded T-shirt bra so that your bust is in the desired position and no additional volume from a padded cup distorts the measurements. Finally, please stand upright and try to read your measurements while maintaining a straight posture.
To determine the size of your panties, it's best to close your legs, stand upright, and measure at the widest part of your hips.