The bridge. This is the part of the frame that goes across the bridge of your nose. That’s why it’s called the bridge.
The temple arm. Those are the parts that connect to the front of the frame on either side of your head and rest behind your ear. Sometimes people call the temple arms “legs,” “stems,” or even “bows,” but in the optical industry they’re called temple arms, because they are next to your temple.
The lens width. This is the diameter of one lens, measured at the widest part. It’s also called the “eye size” in the optical industry, which doesn’t make a lot of sense, because it’s not the measurement of the size of your eye; it’s the measurement of the width of your eyeglasses’ lens. We’re mentioning this because sometimes eye doctors will suggest frame dimensions and write these on your prescription. When they do, they may write “eye size” on the prescription when they mean the lens width. So don’t worry about matching that number with the size of your eye. It’s the width of one eyeglass lens.
The lens height. This is measured just like the lens width, but vertically, not horizontally. If your prescription includes an NV-ADD (Near-Vision reading ADDition) number, you can order bifocal or progressive glasses. This is where the lens height measurement becomes crucial: The lens height must be at least 30 millimeters to accommodate a bifocal or progressive prescription.
The frame width. This is the most important measurement on a frame to determine whether it will fit you well and look good on your face. It’s the measurement of the entire front of the frame, from the point that sticks out farthest on the left, to the point that sticks out farthest on the right. Or vice versa.
Remember when we said in part one that if you have a pair of glasses right now that fits you well and looks good on your face you are ahead of the game? Well, you’re rounding third and heading for home if on the inside of one of your temple arms you have three numbers, which are the dimensions of, in order, the lens width, the bridge, and the temple length.
Most of the time, if the numbers are stamped on the inside of the temple arm, they will be listed the way they are in the first example, on the left. (Ignore the first number on the temple arm that precedes these numbers; that will just be the manufacturer’s model or stock number.)
After this model or stock number, the lens width comes first, the bridge is next, and the temple arm is last. Sometimes it could be listed the way it is in the second example, on the right, with the temple arm length first, the lens width next, and the bridge last. Either way, there will usually be a little square between the first and second numbers.
You may even see a pair of glasses that has these numbers stamped or engraved on the inside of the bridge, but this is rare.
If you have the numbers stamped on the inside of the temple arm or on another element of the frame, the only other measurements you need are the frame width and the lens height.
If you don’t have numbers stamped on the inside of the temple arm, you can measure the dimensions of your frame elements with a millimeter ruler. Don’t have a millimeter ruler? Not a problem; you can get one at any drug or dollar store. However, if you have a cloth tape measure with millimeter hash marks, this would be the best measuring tool to use, especially when we come to the temple arm measurement.
Next, check out part three, to learn how to measure each element we discussed here.