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How to read and measure eyeglasses size

Standard numbers of eyeglass frame size

Typically there will be three standard numbers imprinted on one of the temples or the bridge, indicating respectively the sizes of three frame parts. A typical example is 50-21-142. All sizes are marked in millimeter.

1. Lens size:

The first number 50 represents the lens size, which is also called eye size or lens width. Lens width is the most exact name of this size, describing precisely the distance between the vertical sides of a rectangle containing the lens shape. It is important to differentiate it from lens height. A large lens for a big guy usually has big sizes at both dimensions. Lens size typically ranges from 44 to 52. In rare cases, big and tall guys need to take a frame with a size of 58.

2. Bridge length:

The second number 21 represents the bridge size. Other sayings include bridge length and bridge width. In detail, it is the minimum horizontal distance between the nasal surfaces of the rims. This size varies only slightly because people's noses will hardly differ significantly. When the frame is sitting too high on the face, it is necessary to increase this bridge size. In opposite, a shorter bridge is needed when the frame sits too low on the face.

3. Arm length:

The third number 142 describes the length of an arm or temple. This is the whole length of a temple, consisting of the length to the bend and the length of the drop. Most people can get fit into a size of 140, but a big guy may require 155 and even more.

How to measure eyeglasses size

Step 1: Prepare a metric ruler

Get a metric ruler that is capable of measuring millimeters, the universal unit of measurement set by worldwide frame manufacturers and opticians.

Step 2: Place the frame properly

Place the frame on a smooth table or level surface. It is acceptable whether the arms are closed or open.

Step 3: Align the ruler and make measurements

Align the starting end of the ruler with the one side of the eye rim at the outer edge, and measure the distance to the other side of the eye rim. The bridge length can be measured in a similar way.

Step 4: Measure arm or temple

It is necessary to measure the length to the bend and the length of the drop respectively.

At some online optical shops, customers are required to provide the frame sizes according to personal facial size. This is the necessary information for opticians to fit a pair of comfortable glasses.