Buying eyeglasses online can be a convenient and cost-effective way to get the perfect pair of glasses that suits your style and vision needs. However, one of the key factors to consider when purchasing eyeglasses online is getting the right size. Here is a guide to help you buy eyeglasses with the right size:
To determine the proper eyeglass size for your face based on the roller frame width, lens height, and lens width, you will need to take the following steps:

1. Measure the roller frame width: Use a ruler or measuring tape to measure the width of the roller frame of your glasses. The roller frame width is the distance between the two temples (arms) of the glasses, from one end to the other. It's between 120mm to 150mm
Frame Width Size
Extra Narrow: 126mm-129mm
Narrow: 130mm-133mm
Medium: 134mm-137mm
Wide: 138mm-141mm
Extra Wide: 142mm and above

2. Measure the lens width: Measure the width of one lens from the outer edge to the inner edge not outer edge. This measurement should be taken at the widest point of the lens. It's between 46mm to 60mm
Lens Width Size
Extra narrow: 46-48mm
Narrow: 48-50mm
Medium: 51-53mm
Wide: 54-56mm
Extra wide: 57mm and above

Measure the lens height: Measure the height of one lens from the top to the bottom of the lens. This measurement should be taken at the widest point of the lens. It's between 30mm to 50mm

Once you have these measurements, you can use them to determine the appropriate size for your face. Generally, the width of the roller frame should be slightly wider than the width of your face, to ensure a comfortable fit. The lens height should be proportionate to the distance between your eyes and the bridge of your nose, while the lens width should not be wider than the width of your face.
By following these steps and using the measurements of the roller frame width, lens height, and lens width, you can find the right eyeglass size that will fit your face comfortably and securely.