Bra Size 34: The 34 Band

The band number is a ribcage measurement. Wrap a tape snugly around the torso directly under the breasts, level all the way round, on a normal exhale, and read it: 33 or 34 inches is a 34 band. Nothing is added. Charts that add four or five inches would call the same ribcage a 38, which is why so many people have worn a 38 band that rides up and a cup two letters too small; the methodology page explains why this site never adds inches.

A snug tape reading of 33 rounds up to the 34; a reading of 35 rounds up to the 36. When the tape lands on the odd number it is worth trying both neighboring bands with the cup adjusted a letter, which is what sister sizes are for. Bands are cut in two-inch steps because the elastic covers the inch between; a 34 on the loosest hook fits 33 and 34, and the tighter hooks are there for when the elastic relaxes.

A sister size holds the same cup volume on a different band: one band down and one cup up, or one band up and one cup down. The table shows two steps in each direction from every 34 size, which is as far as sister sizing is useful; beyond that the band is four inches from your ribcage and no cup letter fixes it. Use the first step when a brand runs tight or loose, or when the cups fit and the band does not. Use the second only to understand why a 38 with a small cup never fitted.

The sister size calculator explains which direction to step from any symptom; the bra too big and bra too small pages read the signs.

The 34 band is the center of the retail block and the band most brands cut their sample in. It sits inside the 32 to 38 block where the retail data clusters and where nearly every brand cuts every cup it makes, so a measured 34 has the widest choice on the ladder: every cut, every construction, A to K. That is also its trap. Because the block is where the stock is, fitters and charts pull nearby bands toward it: a measured 30 becomes "a 32 with a smaller cup," a measured 40 becomes "a 38 on the loosest hook." If you measure a 34, you are already in the block and the choice is real; if you were fitted into a 34 from a different measurement, the sister ladder below shows what you should be wearing.

Brands whose charts cut the 34: every brand in the dossiers, every cut, A to K. Each brand page on this site lists the exact band and cup range and notes how that brand’s 34 runs; the best bras by size hub groups them by the cup you need.