Your breasts should be fully contained. If there is puckering in the fabric, the cup is too big; if there is "overflow" at the top or sides, the cup is too small. Fabric and Maintenance
You should be able to fit two fingers between the strap and your shoulder. They shouldn't dig in or slip off. how to buy a sports bra
Different activities require different levels of breast support to prevent discomfort and tissue damage. Your breasts should be fully contained
Size often differs between brands, so always perform these three checks before buying: the cup is too big
Best for yoga, walking, or Pilates. These usually have thinner straps and lighter fabric.
Designed for hiking, cycling, or power walking.