Use our online strength calculator to find your ideal strength in reading glasses, blue light glasses and reading sunglasses from your prescription:
Welcome to our reading glasses prescription calculator page which is designed to help you select which strength reading glasses are the best for your visual needs.
Firstly, we must stress that this does not replace regular eye tests and consultations with your optician.
The prescription you use here must be no more than two years old. Please follow the instructions in the Help & Advice section.
• Enter the values for sphere
and near add
from the drop down menus, as they appear on your prescription for each eye. The axis value on your prescription can be ignored and is not required for this calculation.
• Make a decision as to what the reading glasses are required for
, either for reading
(near or close work such as reading a book, sewing or using a phone or tablet) or for using a desktop or laptop computer
• Also select which is your dominant eye
. This would be the eye that you would use to aim. If you are unsure you can point at a distance object with both eyes open and then close one eye at a time. The eye which is pointing directly at the object
should be your dominant eye, the other will be off to the side.
Please feel free to contact us
should you need any further help.
Should you not have a prescription available, your optician
will also be able to tell you your ideal strength reading glasses either if they have your current glasses prescription on file or at the completion of an eye test.
Alternatively, as a good approximate guide to your reading strength please download and print out our eye chart
which is in PDF format:
Download Eye Chart
Reading Glasses & Strength
There may come a time in your life when the quality of your vision may begin to deteriorate.
Mostly this change comes with age and often means you will require reading glasses for small print, close work or even watching tv.
This change is quite normal and can happen even if you’ve enjoyed perfect vision throughout your earlier life.
The start of deterioration in sight often occurs around the age of 40+.
The technical term for this condition is presbyopia, a natural, age-related change in the lens of the eye which makes it more difficult to focus on smaller print and close-up objects.
The condition may gradually worsen as you near 60 years of age, depending on the type of near distance tasks you are performing.
This process of course varies from person to person and some people may be lucky enough to have perfect 20/20 vision all their lives.
If you have never needed prescription glasses before for conditions such as astigmatism or long-sightedness then you can correct presbyopia with non-prescription reading glasses.
Due to the progressive nature of presbyopia, people around the age of 40 tend to benefit from using low power reading glasses.
These don’t require a prescription and can be purchased here online, directly from our website. As you age, typically around the age of 60, the strength of your reading glasses will need to increase.
Again, these can be easily obtained and you don’t need a prescription. This page will assist you in how to choose the right strength reading glasses.
How to Choose Reading Glasses Strength Accurately
The strength of all reading glasses is measured in dioptre, with units increasing by 0.25 dioptre depending on the power of the lens.
The power of ready to wear reading glasses ranges from +0.50 dioptre to +5.00 dioptres.
Both lenses are the same power, which is usually indicated by a permanent marking on the inside of the frame or with a removable sticker on the lens.
The important thing to remember when choosing reading glasses is, the higher the number, the greater the power or magnification of the lenses.
So, glasses with a marking of +1.00 are low power, while those with a marking +5.00 are high powered.
You can conduct your own reading glasses test by using a reading glasses calculator/dioptre chart as linked above on this page.
Simply position the chart at a distance of around 14 to 16 inches from your eyes (or how you would read a normal-sized print) to determine the strength of the lens you require.
However, this should only be used as an approximate guide to determine a reading glasses strength for you.
If however you already have a written prescription from your optician then he/she will have accurately tested both eyes and written out the appropriate specifications for you.
In this instance you can use enter the values above using our calculator and following the instructions provided will allow you to calculate the ideal reading strength for you.