Please take the measurements of a similar clothing item you already own which fits you well (e.g. if you are shopping for a button up, please measure a non-stretchy button up you already own if possible). Lay it flat on a surface before measuring, then compare those measurements to the size chart in the listing.

Do not use your body measurements. Why? Because everyone's body is a different shape. Two people can have the same chest circumference but different waists, and need different sizes of a shirt. Garment measurements are also inherently different from body measurements because extra fabric is needed to account for movement and flexibility.