How to choose the right strength reading glasses

Firstly : the higher the number the stronger the magnifying power.

Here is a guide correlating age and strength:

1. 40's +1.00 to +1.50
2. 50's  +1.75 to +2.25
3. 60's +2.50 to +3.00
4. 70's +3.50 to +4.00

Please bear in mind there are always exceptions!

A couple of considerations:

1. Reading in a well lit room or a dimly lit room will make a big difference. 
2. You will need extra magnification if the print is very small.
3. You may like to read your book quite close, if so a weaker strength will suffice, if further away you will need a stronger strength.
4. There is not an enormous difference between +1.50 and +2.00 and obviously less between +1.50 and +1.75.
5. We would suggest you prioritise your comfort. You don't want to be straining your eyes.
6. If unsure, your optician will sort you out.