Free Tool
Reading Prescription Calculator
Find your reading glasses prescription and the closest over-the-counter reading power.
Right Eye (OD)
Right Eye (OD)
Enter prescription to see results
Right Eye (OD)
Enter prescription to see results
Left Eye (OS)
Left Eye (OS)
Enter prescription to see results
Left Eye (OS)
Enter prescription to see results
How the Reading Calculator Works
As we age, the eye loses the ability to focus up close — a condition called presbyopia. Optometrists add an ADD power to a distance prescription to correct this. The ADD is always a positive number, typically between +0.75D and +3.50D.
Your reading glasses prescription is calculated by adding the ADD power to your distance SPH. The CYL and AXIS remain unchanged:
The closest over-the-counter (OTC) reading power is derived using the spherical equivalent — a single SPH value that approximates the full prescription (including cylinder) as a simple sphere:
This result is rounded to the nearest 0.25D. Note that OTC glasses do not correct astigmatism — prescription reading glasses are always recommended for anyone with significant CYL.