To prep for this glasses fit guide, grab a ruler and a pair of eyewear you own that best fits your face (if available).
To get the right sizing for your eyeglasses, take the ruler and measure the width in millimeters from hinge to hinge. If you don't have glasses, then have a friend help your fitting by measuring the width of your face from temple to temple.
The right size frames should have a width of within 4mm of what you measured from hinge to hinge or between your temples.
Many eyeglasses have three numbers that you can find on the inside of the arms. The first is the glasses lens width, the second is the nose bridge width, and the third is the temple length. Or, look for a size chart in the product description on the brand's website.
Even within the frame size, you'll have personal preferences for the width and feel of your glasses.
The bridge connects the two lenses in the frames, and the nose pads are just below the bride to help the frames sit comfortably on your face.