Editorial Policy & Sizing Methodology. Brasize.ai

Sizing methodology

Brasize.ai uses the modern snug-measure method: the band size is the underbust measurement taken snugly and rounded to the nearest even inch; the cup is the difference between the bust measurement at the fullest point and the band, at one inch per cup letter. We do not add four or five inches to the underbust. This reflects current professional fitting practice and modern stretch fabrics.

Conversion standards

International conversions follow the widely-used relationships between systems. Where a system varies by brand (notably Japanese cup grading and US brands that write DDD as F), we say so on the page.

System	Band	Cup letters	Example (US 34C)
US	Underbust, inches, even	A B C D DD DDD G H I J K	34C
UK	= US	A B C D DD E F FF G GG H	34C
EU / DE	US × 2.5 − 10	A B C D E F G H I J K	75C
FR / ES	EU + 15	as EU	90C
AU / NZ	US − 22	as UK	12C
IT	(EU − 60) ÷ 5	as EU	3C
JP	= EU	≈ EU (some charts +1 above D)	75C

Sister sizes and the +4 twin

Sister sizes are computed as band −2 / cup +1 (snugger) and band +2 / cup −1 (looser). The “old-method twin” shown on size pages assumes the traditional +4 rule inflated the band by four inches and therefore understated the cup by two letters: twin = band −4, cup +2.

Review

Guides are reviewed for accuracy against published fitting practice and brand size charts, and each page states when it was last reviewed. Where a claim depends on a specific brand's chart, we cite the brand's own convention rather than a third-party summary. Content is educational and is not medical advice.

Independence

Brasize.ai does not sell bras. Brands are mentioned to explain which sizing system they use. We do not accept payment to feature or rank brands, and no brand influences a calculation.

Corrections

If you find an error: a wrong conversion, an outdated brand convention, a broken calculation: email hello@brasize.ai with the page and the fix. Verified corrections are made promptly and the page's review date is updated.

Review log

Date	Scope	Change
August 2026	Methodology	Version 1.1 published: declared constants added (tape tension standard, rounding rules, baseline declaration) after a 57-brand survey of published size charts showed instructions and grading disagree between brands. Both circulating "80%" claims documented with their actual sources.
August 2026	Correction (our own)	Our homepage repeated the industry claim that the band provides "80% of support" without a controlled source. Caught in our own audit; rewritten site-wide to "most of a bra's support". We applied the same standard to ourselves that we apply to brand charts.
August 2026	Brand data	Knix chart references updated: four pages described the retired 1–8 numeric sizing as current. Corrected to the current alpha sizing; the retired chart is noted as historical.
August 2026	Site-wide	Editorial pass replacing em-dash-heavy phrasing across 915 English pages for readability. No factual content changed.
June 2026	Site-wide	Methodology documented; snug-measure standard confirmed; conversion table published; size guides for US, UK, EU, FR/ES, AU/NZ and IT reviewed.

Ownership

Brasize.ai is published by NativeCode.