Strapless Bra Size Calculator
Estimate a strapless bra size from your underbust and bust measurements, compare international size labels, and check band-fit considerations.
How this strapless bra starting point is calculated
The calculator uses the same core measurement method as the universal bra calculator. It does not claim that every strapless bra needs a smaller size; instead, it gives you a consistent size starting point and then highlights the fit factors that matter most when straps are removed.
- Band: the snug underbust is converted to inches, rounded to the nearest whole inch, then moved to the next even number when needed.
- Cup index: standing bust minus snug underbust is rounded to the nearest whole inch.
- Label: the cup index is mapped to the selected US, UK, EU, or AU cup sequence.
- Strapless fit: the result is checked using band and sister-size guidance rather than applying an arbitrary size reduction.
A strapless bra can fit differently from a regular bra because support comes from the band, cups, wings, grip materials, and garment construction. Use the result as a starting point and confirm the manufacturer's own chart before buying. See the full sizing methodology.
Frequently Asked Questions
Answers about sizing methods, measurements, and fit considerations.
Is a strapless bra the same size as a regular bra?
Usually, the measurement-based starting size is the same, but a strapless bra depends heavily on a secure band and the construction of the garment. Always check the manufacturer's chart.
Should I go down a band size for a strapless bra?
Not automatically. A strapless bra should feel secure without painful digging or restricted breathing. If the band is loose or rides up, a smaller band may be worth trying with the corresponding sister cup size.
Why does the band matter more in a strapless bra?
Without shoulder straps, most of the bra's support and stability comes from the band, cup construction, wings, and grip features. A correct band fit is therefore especially important.