If you own a pair of glasses and need new ones, you can save money by avoiding going to an eyewear center by buying new glasses online using the number already printed on your existing glasses. All pairs of prescription eyeglasses purchased in Canada and the USA have the sizing numbers written on the inside of the arms if they are glasses purchased within the last 6 years. If the number is not found on the arms it will be printed on the bridge of the glasses, the part that sits on your nose.
How to find the sizing number on eyeglasses
The first two numbers affect overall width and the third number is length (all numbers are in mm):
1st number – Lens Diameter – Which means how wide each lens is across.
2nd number – Bridge Width – The space that sits on your nose.
3rd number – Arm Length – This number will normally be in the 100’s.
NOTE – These numbers do not include your Pupillary Distance. This number is required when ordering glasses online but is not usually included with your prescription information you got when you received your existing glasses.
To measure your Pupillary Distance (PD):
1 – Place a mm ruler up against your eyes and rest it on the bridge of your nose.
2 – Line up the starting point at 0mm with your left pupil. (NOTE: This measurement is only accurate if you are looking straight ahead.)
3 – Look directly at yourself in the mirror or have someone else read the ruler. If someone else is reading the ruler they must be at the same height as you.
4 – When the 0mm mark on the ruler is lined up correctly on the left pupil the mark that lands in the center of the right pupil is your distance PD.
Now you should have the complete number set to order your prescription eyeglasses online!