Understanding your size starts with a clearer explanation.

Why this guide exists

A G cup label can mean different things in different countries. Changing a band can change the cup letter you need. A size that looks correct on paper can still leave pressure or empty space in a particular bra. This site separates those questions so you can take a useful next step.

G Cup Bra Guide is the publishing name used on gcupbrasize.com. We provide free educational calculators and written guides for people comparing fuller-bust sizes, with US and UK systems kept explicit. We are an informational website, not a bra retailer or a fitting appointment service.

Choose a tool for your question

Use the bra size calculator to estimate a starting label from two measurements. If you already have a label, use the international size converter. If the band feels wrong, explore adjacent sister sizes. For discomfort, start with the band, cup and wire fit checks.

Style guides ask about the garment and task: movement for sports bras, seated space for longlines, and torso length for one-piece garments. These are decision aids rather than product rankings or promises of support.

How we explain a result

Tools show their assumptions, required inputs and practical limits. Measurement estimation and chart conversion are different operations. We identify the chart used for conversions and decline unsupported combinations instead of inventing labels.

Our sizing methodology explains rounding, cup sequences and chart limits. The editorial policy describes source selection, AI assistance and evidence requirements. We do not claim certified fitter credentials, clinical review or personal product testing.

Privacy while you measure

The calculators run in your browser. They do not send or store your measurements. You can try an example, replace it with your own readings and clear the result. Copying fit notes is optional. The privacy notice explains the separate handling of correspondence.

Help us correct something

A useful correction includes the page address, selected size system, units and what appeared incorrect. A chart name and the label printed on the garment can explain a mismatch. You do not need to send photographs or medical details. Use the contact page to report a calculation or content issue.

We cannot determine your best fit remotely from a cup letter alone. Compare the actual garment, and stop wearing a garment that causes pain.