What do dioptres mean for reading glasses?

The strength of reading glasses is measured in dioptres. This unit of measurement indicates how much the lens refracts light to correct near vision. Lenses are usually rated in 0.5 dioptre increments. A dioptre of +3.00 means you need a lot of correction, while dioptres of +1.50 or less mean you need less correction.

The range of strengths of reading glasses

Reading glasses usually range from very weak corrections of +0.25 dioptres to stronger corrections of more than +2.50 dioptres. However, there are also glasses with up to +4.00 dioptres.

Common strengths for reading glasses

Most people who wear reading glasses need between +1.00 and +2.50 dioptres. This choice depends on individual factors such as age and eye health. The first pair of reading glasses is often less powerful because presbyopia usually starts with a mild visual impairment and worsens over time. Some people eventually need glasses with up to +3.50 or +4.00 dioptres.

The importance of the right prescription

It is important to wear reading glasses with the correct prescription. The wrong strength can cause headaches, eye strain or blurred vision. Wearing the right reading glasses is easier on your eyes and helps you see for longer.

How do you know if you need reading glasses? Read more in our blog post When do I need reading glasses?

How to determine the right strength for your reading glasses

To find the right strength for your reading glasses, you can make this estimate conveniently at home. The required dioptre can be roughly estimated based on your age:

Under 35 years: +0
40 years: +1.0
45 years: +1.5
50 years: +2.0
55 years: +2.5
60 years: +3.0

These values serve as a guide based on typical, age-related changes in vision.

Check your reading glasses prescription online

Use this simple method to test the strength of your reading glasses online:

1. Step: position the chart on your screen about 40cm from your face.
   
   
2. Step: Remove any prescription lenses and read the diagram from top to bottom. You may have to go through several lines until you can recognise one clearly. Cover one eye and repeat the process.
   
   
3. Step: Make a note of the first line that you can read clearly. This probably corresponds to the strength of the reading glasses you need.
   

Click here for the diagram (German)

Important note on visual acuity testing

Please note that the Internet visual acuity tests are for guidance only. They are not a substitute for professional examination by an optician or ophthalmologist. We strongly recommend that you have a professional eye examination to ensure that your visual acuity is accurately determined and that you receive the best possible correction. Only a qualified optician or ophtalmologist can provide a comprehensive diagnosis of your vision and recommend appropriate vision correction.