How to measure bra size and understand your result

Before you measure

Use a flexible measuring tape rather than a rigid ruler. Keep it level around your body, and take the measurement without pulling the tape into your skin. You can measure without a bra or over a lightly lined bra, whichever is comfortable. A heavily padded bra can change the bust measurement.

Choose inches or centimeters before entering your numbers. The calculator converts centimeters to inches internally using 2.54 centimeters per inch. Changing units converts the same measurements; it should not change the physical size being described.

Quick: two measurements

Underbust is the circumference directly beneath the bust. Bust is the circumference around its fullest part. In Quick mode, the model rounds the underbust to the nearest even band size and compares the bust measurement with that band to estimate a cup index.

This is a starting-point model, not a promise of fit. Two people with the same circumferences can prefer different bras because shape, fabric stretch, cup construction, and comfort are not captured by those two numbers.

Advanced: six measurements

Measure the underbust loosely, snugly, and tightly, then measure the bust while standing, leaning, and lying down. Keep the tape gentle; tight does not mean painful.

The current model estimates its band reference from 70% of the snug underbust and 30% of the tight underbust, then rounds to an even band. It averages the three bust measurements for the cup calculation. The loose underbust and the spread between measurements help describe uncertainty. These are prototype rules, not independently validated fitting guarantees.

Worked example: why the label is only a starting point

With a 32-inch underbust and a 36-inch bust in Quick mode, this model chooses a 32 band. The four-inch difference corresponds to D in its baseline US cup sequence, giving 32D as an example starting label. It does not add four inches to the underbust.

A 32D from one brand or style can feel different from another. Treat the example as an explanation of the arithmetic, not a recommendation for your body. If your measurements are outside the model’s supported range, the calculator stops rather than inventing a result.

Sister sizes and conversions

A sister size pairs a neighboring band with a compensating cup step to describe approximately similar cup volume. A tighter-band alternative is not the same fit as the original size: the band tension and the proportions change. Try a neighboring size because of how the garment fits, not because the number is supposedly better.

US, UK, EU, French, and Australian labels shown by this tool are approximate conversions. Cup sequences and brand charts vary, so use the official size chart for the exact brand and style before buying.

What a brand match does—and does not—mean

The directory contains brand names for discovery, but only a small subset has reviewed sizing profiles. Pending names cannot be selected as supported sizing choices. A reviewed label chart maps the baseline estimate to a published label; it does not validate that a particular bra will fit.

Bali’s current manufacturer guide uses snug underbust rounded upward to an even band, without adding four inches, and standing bust minus that band for the cup. Its supported guide subset uses those two measurements even in Advanced mode, so the Bali result can differ from the general six-measurement estimate. Other product lines or retailer guides may use different methods; do not mix their instructions.

Follow the official chart link, check the listed source date and limitations, then compare how the whole bra feels. The calculator does not diagnose health concerns or replace a professional fitting. Persistent discomfort deserves attention rather than repeatedly forcing a size label to work.