- US starting size
- 32D
- Band
- 32 in
- Rounded cup difference
- 4 in
About this result
A fitting starting point using the stated US cup ladder, not a universal brand or international conversion. Positive half-inch rounding ties go upward.
How it works
Compare methods with identical measurements
Keep bust and underbust fixed when comparing direct-underbust and traditional +4/+5 methods. A changed band or cup then reflects the convention, not a body change. Record the method alongside the label when comparing recommendations from different shops.
Using a size estimate as a fitting starting point
Bra-size methods and regional labels can differ, so choose the system and measurement approach that match the question. Keep underbust and bust measurements distinct, and check the requested units. A converted label or formula result is a fitting starting point rather than a guarantee across brands and styles. Dress-label conversion is a separate comparison and does not infer fit from bra size.
US starting size: formula and assumptions
Round the underbust to the nearest even band; cup is the bust-minus-band difference in inches.
Uses a modern direct-underbust US starting-size convention. Brand, style, measuring technique, and regional lettering differ.
Traditional +4/+5 band estimate: formula and assumptions
Round each inch measurement; add 4 to an even underbust or 5 to an odd underbust, then compare rounded bust with band.
Alternative traditional fitting method using a declared US cup ladder: difference 0 = AA, 1 = A, 2 = B, 3 = C, 4 = D, then DD, DDD, G–L. This convention is not a universal fit or international brand conversion.
International bra label conversion: formula and assumptions
Match the band and cup independently in the Wacoal international convention.
Uses the named Wacoal convention, including AA where listed and distinct UK, US and European cup ladders. Only the documented band and cup ranges are supported. This converts garment labels, not measurements or dress sizes.
Dress label conversion: formula and assumptions
Match the size within the Wacoal dress-label conversion rows.
This separate garment-size conversion does not determine bra size. Bra band and cup depend on additional measurements and the garment convention.
Worked example
Using the US starting size example:
- Measurement units
- One unit for all measurements
- Measurement unit
- Inches
- Snug underbust (in)
- 32
- Full bust (in)
- 36
Round the underbust to the nearest even band; cup is the bust-minus-band difference in inches.
Example result
US starting size: 32D
Band: 32 in
Rounded cup difference: 4 in
- A fitting starting point using the stated US cup ladder, not a universal brand or international conversion. Positive half-inch rounding ties go upward.
These are illustrative inputs. Change the values to explore a different scenario.
What to keep in mind
Try-on fit matters more than the estimate. This does not implement a universal international sizing standard.
Formula references
- NIST: Guide to the SI (opens in a new tab)
- Triumph: traditional +4/+5 measurement method (opens in a new tab)
- Wacoal: international band, cup and dress label conventions (opens in a new tab)
References explain the underlying methods; they do not imply endorsement or individual professional review of Finflo.
Common questions
Is the suggested size a universal international conversion?
No. The tool uses a US starting-size convention. Regional cup lettering, brands and styles can differ.
Why might a different size fit better than the estimate?
Measurements, garment construction, shape and personal fit preferences affect the result. A calculated starting size does not replace trying the bra on.
Prepared by Finflo. See our methodology and editorial policy.