Last updated: August 29, 2026

About BraFitly

BraFitly is a free online bra-sizing and fit-education resource designed to make measurement, size comparison and fit guidance easier to understand.

What BraFitly provides

BraFitly provides a browser-based main bra size calculator, international size references, a sister-size calculator, bra-fit guidance, and dedicated pregnancy and nursing sizing tools. The site does not sell bras.

Why the calculator exists

Bra sizing is not a single universal standard. Labels can vary between countries, brands and styles, so BraFitly is designed to give visitors a practical starting point from two measurements rather than presenting a result as a guaranteed perfect fit.

How the calculator works

  1. You enter an underbust and bust measurement in inches or centimetres.
  2. The underbust is mapped to a nearby even-inch band starting point.
  3. The difference between bust and band is used with a reference cup sequence to estimate a starting cup.
  4. The result is mapped to common international reference systems.

The model is intentionally transparent and simplified. It is not a reproduction of any individual brand's proprietary fitting process.

Accuracy and limitations

Actual fit can differ because brands and styles use different cup shapes, wire widths, materials, grading and fitting conventions. Body shape and measurement technique also matter. For that reason, BraFitly describes results as estimates and recommends checking the current size chart and actual fit of the specific garment.

Methodology and reference approach

BraFitly compares its sizing logic and educational guidance against established bra-fitting and international sizing conventions. These conventions can vary between brands and markets, so BraFitly does not treat any single chart as a universal guarantee of fit. Results are presented as starting-point estimates.

Pregnancy and nursing tools

The pregnancy and nursing calculators estimate a current size from current measurements. They do not predict future body changes and are not medical, pregnancy or lactation advice.

Contact BraFitly

For corrections, feedback, privacy questions or technical issues, email contact@brafitly.com.