36H and 38G are sister sizes — the same cup volume worn on a band that's 2 inches different, 36H being the snugger, more supportive option and 38G the looser, roomier one.
36H and 38G are sister sizes — the same cup volume worn on a band that’s 2 inches different, 36H being the snugger, more supportive option and 38G the looser, roomier one.
Plenty of women bounce between 36H and 38G for years without ever being told both fit the same body the same way.
Why 36H and 38G Hold the Same Volume
A snugger band carries more of the support load directly against your ribs, so the cup itself can be smaller. Loosen that band and the cup has to pick up the slack the band used to handle.
In practice: 36H pairs a tighter, more supportive band with a smaller cup letter, while 38G pairs a looser band with a bigger cup letter — both are carrying the identical amount of breast tissue, just distributed differently.
This comes up constantly when a store is sold out of one size but has the other in stock — it’s genuinely worth grabbing the sister size rather than leaving without trying anything on.
Signs You Need the Snugger 36H Instead
Lean toward 36H if the straps are doing most of the lifting and digging into your shoulders because the band isn’t holding its share. A band that isn’t doing its job shows up as strap and shoulder problems long before it shows up as an obvious “this is loose” feeling.
Signs You Need the Roomier 38G Instead
Lean toward 38G if the center gore (the bit between the cups) doesn’t sit flat against your sternum. Cup problems are usually easier to spot than band problems, but they get blamed on “bad luck with bra shopping” far more often than they should.
Which One Should You Try First
A quick test: if your current bra’s band rides up your back within an hour, go for the tighter band. If the band feels fine but the cups gape or wrinkle, the looser-band option is worth trying.
Not sure which of these two is actually your size? Run your measurements through the Sister Size Calculator or the Main Bra Calculator — both are free, private, and take under a minute.
Style Considerations
Balconette and demi styles tend to work well here since they don’t rely on excess fabric to create shape.
This Can Change Over Time
Body measurements can shift slightly with the seasons for some people — a bra that fit perfectly in summer can feel different after a few months, which is normal and worth a quick re-check rather than assuming something’s wrong.
Shopping Tips
Reading recent reviews that mention true-to-size feedback for the exact style (not just the brand generally) is one of the more reliable ways to predict fit before buying online.
FAQ
Often yes — very small or very large bands in a given cup letter tend to be less common in physical stores, so the sister size can be a useful workaround when your first choice is sold out.
Most do, since the underlying math is standard across the industry, but cut and construction still vary by brand and style — always sanity-check against that brand's own size chart.
Often yes, especially for underwire swim tops built like bras, but swimwear sizing is less standardized across brands than everyday bras, so treat it as a starting point, not a guarantee.
Not identical — the cup volume is the same, but a tighter band feels different against your ribs than a looser one. Most people have a genuine preference once they try both.
Often yes — sports bras use different construction (more compression, less structured cup shaping) that can make the same labeled size feel noticeably different from an everyday style.
Yes, for most people — weight change, age, hormonal shifts, and even different laundry habits can all move the number gradually, which is why periodic re-measuring matters more than getting it right once.
Mid-morning to early afternoon tends to be most representative for most people — very early morning or late evening can show minor temporary swelling that isn't your typical baseline.
