Here’s how to measure each element we discussed in the previous article: How to measure an eyeglass frame, part two:
The bridge. Measure horizontally, at the top of the bridge, from the edge of one lens to the edge of the other lens. The part of the frame that holds the lenses in place will be included in the measurement, since you’re measuring from lens edge to lens edge, not frame edge to frame edge.
The temple arm. This is the measurement for which a cloth measuring tape with millimeter hash marks would come in handy. Here’s why: The temple arm is measured from the hinge, where the temple arm connects to the front of the frame, all the way back to the tip.
The measurement includes the bend around the ear, which is why a cloth tape measure is useful for this measurement. If you have a cloth tape measure, you can measure the curve easily. If you’re using a plastic or wood straight-edged ruler, it would be best to do the measurement in two parts.
Start at the hinge, measure to the beginning of the bend, and write that measurement down. Then go back to where you left off, right at the beginning of the bend. Measure the last part, which is angled, to the tip. Add the two sectional measurements together, and that’s the total temple arm length.
You may have a pair of glasses with cable temple arms, the kind that curve around your ear.
If you don’t have a cloth millimeter tape measure, you could print out the downloadable PD ruler at the Zenni Optical website.
You can use this paper ruler to measure the cable temple arm. Or you could cut a strip of paper about a half-inch wide and 10 inches long. Mark the little paper strip where you begin measuring the temple arm at the hinge. Curve the paper strip around the curve of the temple arm and mark it where the temple arm ends.
Stretch out the paper strip and measure the length with a millimeter ruler. That’s your cable temple arm length.
The frame width. Again, it’s the entire horizontal measurement of the front of the frame, measured from the part that extends farthest outward on one side to the part that extends farthest outward on the other side. A metal frame may have a little piece that sticks out on the side toward the top, like the part that extends from the outer edge of the lens on a pair of rimless glasses, just before bending to meet the hinge of the temple arm, such as on this rimless frame:
If you do have a frame such as this one, or any frame with a piece that sticks out on the side, you would include that part of the frame, on each side, in your measurement of the frame width. Whether a frame is too big, too small, or just right for your face is mostly determined by the frame width. Also, make sure you do this measurement at the front of the frame. You don’t need to measure the distance between the two temple arms at the back of the frame.
The lens width. If the width of the frame you are shopping for online matches within two or three millimeters the width of the frame you have that fits you well, you can be confident that the frame you see online will fit you just as well. But be aware of the lens width: even though the total frame width might match the width of your frame, the lens width might be a little narrow or wide for your pupillary distance, which is the measurement of the distance between the middle of each pupil. This measurement determines where to place the optical center on each lens.
The lens height. This is measured just like the lens width, but vertically, not horizontally. Once again, the lens height must be at least 30 millimeters to accommodate a bifocal or progressive prescription. In addition, pay attention to the lens height, because this is an important factor in determining how the glasses will look on your face. If you get a frame with a tall lens height, something over 36 millimeters, the glasses may look too big for your face. Conversely, a too-short lens height, lower than 30 millimeters, may not provide all the corrected-vision coverage your eyes need.
How to measure an eyeglass frame, part four, the last part, will describe how to shop for a frame online that will fit you, now that you know the dimensions you need.