Bra Fitting for Trans Women
When we searched the web for resources on bra fitting for trans women, we found an astonishing lack of information. The few guides available suggest outdated methods of adding inches to the band size and these methods overestimate band size and underestimate cup size for both trans and cis women.
We referenced previous fit/measurement checks from trans women and found that the ABTF methods overestimate cup size by two cups on average. We believe this overestimation is due to differences betwee the ribcages of trans and cis women. Specifically, trans women's ribcages tend to be more V shaped, which means that more of the bust measurement is taken up by the ribcage than breasts.
Based on previous fit/measurement checks, we determined the most accurate way to calculate bra size is to use a soft measuring tape and the visual fitting guide to measure:
Snug Underbust (#1)
Tight/Break the Tape (BTT) Underbust (#2) (optional)
Laying Bust (#5)
Using these measurements, determine the difference in your underbust and standing bust:
Difference = Laying Bust - Snug Underbust
This difference is used to determine your cup size, and your snug underbust is your band measurement. Many trans women tend to have shallow breasts (e.g., the tissue is spread out rather than projected) so we recommend checking out the Shallow Breast Guide.
(Placeholder for cup-size table)
If your snug underbust is an odd number, then round to the nearest even number. Sometimes when there is a large difference between the snug underbust and BTT underbust we recommend women size down in the band (e.g., your snug underbust measures 33.5 and your BTT underbust measures 30.5, we may recommend trying a 32 band instead of a 34). That said, trans women may have similar fit issues to muscular women (see this blog post) which means that you may want a band close to or possibly larger than your snug underbust measurement. If you have a lot of squish (a large difference between Snug and Tight Underbust measurements), then you may be more comfortable (or need to) size down to a smaller band size.
Note: If your snug underbust is 36 or more, please make a measurement check post on /r/ABraThatFits for more individualized help since our standard guide can yield inaccurate results.
The bra size that you calculate should be your proper size (or close to it). Sometimes bra fitting is more art than science so you may need to go up/down in cup and band size. This may vary depending on the bras brand and model (e.g., most women go up a cup size in Cleo Juna). Knowing how to troubleshoot will help you determine if you need to move up/down cup size(s).
