A marking such as 52–19–145 usually describes lens width, bridge width, and temple length in millimeters. These three numbers describe parts of the frame; they do not guarantee a comfortable fit or tell you its overall width.
Write down the numbers on your current pair and note what you would change: slipping, pressure at the temples, or arms that feel too short. Compare the listed dimensions on a product page rather than relying only on a small, medium, or large label.
Check lens height and overall frame width when available. Similar lens and bridge numbers can still produce a different fit because frame construction and shape vary. Ask for clarification before ordering when a dimension is missing.
Use virtual try-on to explore appearance. An illustrated preview cannot measure pressure, confirm physical fit, or establish prescription suitability.