Your eyes turn inward when reading, so your "Near PD" is typically 2-3 mm narrower than your "Distance PD".

Many retailers like Zenni Optical or Warby Parker offer online tools or printable rulers to measure this at home. 3. Choose Your Lens Type How to Convert Eyeglass Prescription to Reading Glasses

Use this formula for each eye separately: .

If SPH is -2.00 and ADD is +2.25 , your reading power is +0.25 .

If SPH is +1.00 and ADD is +1.75 , your reading power is +2.75 .

To buy reading glasses using a prescription, you must use your distance and Addition (ADD) values to calculate the correct lens power . 1. Calculate Your Reading Power

If your prescription has Cylinder (CYL) and Axis numbers, copy them exactly; they do not change for reading glasses. 2. Adjust Your Pupillary Distance (PD) PD is the distance between your pupils in millimeters.