Why Use an Online Ring Size Chart? Shopping for rings online can be tricky since you can’t physically try them on. That’s where an online ring size chart becomes invaluable. It allows you to measure your size from the comfort of your home using digital or printable tools. With accurate measurements, you can avoid the hassle of resizing or returns. Our printable and real-size chart displays measurements in millimeters (mm), centimeters (cm), and inches, and includes U.S., U.K., and international conversions, making it ideal for shoppers worldwide. It’s a smart, simple, and reliable way to find your ring size before placing an order. How Ring Sizes Are Measured Understanding how ring sizes are calculated can help you interpret the chart more accurately. There are two key measurements to know: diameter and circumference. Diameter: The distance across the inside of the ring (measured in mm or inches). Circumference: The distance around the inner circle of the ring (measured in mm or cm).