How to measure PD for online glasses

Option	Typical cost	Choose it for	Risk level
Online order	Lower to medium	Known measurements and straightforward needs	Medium
Home trial route	Medium	Frame fit is uncertain	Low to medium
High-street optician	Higher	Varifocals, prism, strong prescription or fitting uncertainty	Low

What is PD?

PD stands for pupillary distance: the distance between the centres of your pupils. Online glasses retailers use it to align the optical centres of your lenses with your eyes.

Why it matters

Small errors can matter more for stronger prescriptions, varifocals, prism and larger frames. If your prescription is complex, it is worth asking the retailer or an optician for guidance rather than guessing.

How buyers usually find it

Some prescriptions include PD, but many do not.
Some online retailers provide measurement tools or instructions.
An optician may be able to measure it for you.
For varifocals or complex lenses, fitting height and frame position may also matter.

Common online-ordering mistake

Do not copy a number from old glasses paperwork unless you know what it represents. Some documents show a single binocular PD, while others show separate right and left values. Entering those in the wrong place can affect lens positioning.

When not to measure it yourself

If you are ordering varifocals, strong prescriptions, prism lenses or glasses for a child, ask for professional guidance. PD is only one part of fitting; some orders also depend on frame position and fitting height.

What to check before checkout

Make sure the retailer's form matches the values you have: one combined PD, or separate right and left PD. If the site asks for something you do not understand, pause and contact support before paying.

Affiliate disclosure: Some retailer links may earn commission at no extra cost to you. We still compare retailer suitability, caveats and alternatives before linking out.

Use PD as part of the wider order check

PD matters, but it is only one part of online ordering. Frame size, prescription type, lens choice and return terms still need checking before checkout.

Read buying guide

How PD affects retailer choice

Some retailers make PD entry simple; others expect the buyer to already know the value. If you are not confident measuring PD, choose a retailer with stronger support or consider an optician-led route.

PD matters more for stronger prescriptions, larger frames, varifocals and any order where lens centration is sensitive. Guessing can turn a cheap order into an unusable pair.

Check PD with the full order

Pair this guide with the retailer comparison, delivery and returns guide, and checkout checklist before placing an order.

Compare retailers Checkout checklist

Before entering PD online

Use this page as the first decision point. First, decide whether the order is low risk or fitting sensitive. Then open the relevant retailer review and compare the same basket across at least two retailers. The useful comparison is the full order after prescription lenses, coatings, thinning, delivery, discount terms and returns are included.

For a lower-risk order, such as a familiar single-vision spare pair, the buyer can focus on price, delivery and basic return clarity. For a higher-risk order, such as varifocals, a strong prescription, reglazing valuable frames or prescription sunglasses for driving, the buyer should give more weight to measurement support, lens advice, production expectations and aftercare.

UK Glasses Guide is designed to make those trade-offs visible. Retailer pages explain where each shop may fit, while the guide pages explain the optical and service questions that are easy to miss during checkout. If a retailer page and a guide point in different directions, choose the safer route for your prescription and use case.

Price check	Compare the total order cost with the same lens package and delivery route.
Fit check	Confirm PD, frame measurements, bridge fit and any fitting-height requirement.
Service check	Read production time, return terms, remake process and support route before paying.
Safety check	Use an optician when the prescription, eye health or fitting need is complex.

Checked on 26 April 2026. Retailer information, comparison notes and source links are reviewed for buyer relevance, but prices, codes, delivery times and policies can change without notice.