The ADD number on your eyeglass prescription is the additional magnifying power prescribed for the reading or near-vision zone of multifocal lenses such as progressives or bifocals. It is always a positive value, typically ranging from +0.75 to +3.50, and it applies equally to both eyes even if only one value is written.
What Does the ADD Number Actually Mean?
Your eye has a natural ability to shift focus between near and far objects — a function called accommodation. As you age (usually from your early 40s onward), this ability weakens, a condition called presbyopia. The ADD value compensates for this loss by boosting the lens power in the reading zone of your glasses. A higher ADD number means your near-vision needs more assistance.
Where Do You Find ADD on a Prescription?
Look at the bottom row of your prescription. It is usually labelled ADD or Near ADD. Your prescription will also include columns for SPH (sphere), CYL (cylinder), and AXIS — those values describe your distance correction. The ADD sits separately because it is an addition on top of your distance power, not a replacement for it.
Sample Prescription Layout
A typical prescription might look like this: OD (right eye) SPH -2.00, CYL -0.50, AXIS 180 — and then at the bottom, ADD +2.00. That same ADD value usually applies to OS (left eye) as well. If your optometrist writes it only once, assume it covers both eyes.
Which Lens Types Use the ADD Number?
Not every pair of glasses uses the ADD value. It is relevant only for multifocal lenses:
Progressive lenses — a seamless gradient from distance to near power, no visible line
Bifocal lenses — a visible line separating the distance and reading zones
Reading glasses — if prescribed as standalone readers, the ADD value may be used directly as the full lens power
Single-vision distance glasses do not use the ADD value at all. If you order single-vision lenses on Rimloo, you will only fill in your SPH, CYL, and AXIS.
ADD Number vs SPH: What Is the Difference?
The SPH corrects your distance vision — it is the baseline correction for your eyes at rest. The ADD is an extra boost applied only to the near zone. To find the actual near-vision power of a multifocal lens, opticians add the two together. For example, if your distance SPH is -2.00 and your ADD is +2.00, your reading zone power is effectively 0.00 (plano), meaning you need no correction for near objects when focused through that zone.
What ADD Value Is Normal for Your Age?
ADD values typically increase with age. A person in their early 40s might need only +1.00, while someone in their mid-50s or older commonly requires +2.50 or more. Your optometrist determines this through a refraction test — never self-diagnose or borrow someone else's reading glasses based on guesswork.
How to Enter ADD When Ordering Glasses Online
When you place an order on Rimloo and select progressive or bifocal lenses, you will see a dedicated ADD field in the prescription form. Enter the value exactly as written on your prescription, including the plus sign. If you are unsure, contact our support team before placing your order — getting this right is essential for accurate lenses.
