To buy your ideal pair of spectacles, you will need to first identify the size of the current spectacles you wear.  This is called the Frame Size.  

The frame size will tell you the lens width, nose bridge width and the length of the arm/ sides of your spectacles.  Sometimes, they can also include the depth of the spectacle lens,   You can find these relatively easily on the inside of one arm of the spectacles or situated on the inside of the nose bridge.  Let us help you identify these measurements.

You will need:

  • Your Glasses
  • Somewhere to note the measurements down 

Understanding Your Frame Size

All measurements are usually found on the left arm of your glasses and diplayed in millimetres. They will include lens width, bridge width and arm length as shown below:

frame size

Lens Width

lens width


The lens width is usually 40mm-62mm. This measures how wide each lens is on the frame.

Bridge Width

bridge width


The bridge width varies between 13mm-20mm. It tells you how wide the gap between the frame lenses are.  This is especially important when choosing plastic frames as they determine how well the frame will sit on your nose.

Lens Depth

lens depth40 mm

The lens depth is measured from the top of the frame inner rim to the bottom inner rim.  It lets us know if a frame is suitable for varifocals lenses as these lenses require some depth to get the best field of vision. 

Side Arm Length

side arm length


The arm length can vary between 130mm-145mm for adult glasses, It measures the length of the sides from the temple to the tip.  This measurment is important so that the glasses fit comfortably round your ears.

These measurements are important as they tell us how good a fit the frame will be.  Try to purchase a frame to the same/ or as close a measurment to your own. If in doubt please contact us for guidance.

WIth our guide above, you should be able to identify the important measurements.

Together, they will give you the measurements you need to be able to pick out your perfect pair of spectacles.