Single or Binocular PD
63 mmOne number measured from the center of one pupil to the center of the other.
PUPILLARY DISTANCE MEASUREMENT GUIDE
How to Measure Your PD at Home for Prescription Glasses
Pupillary distance, usually called PD, is a fitting measurement used to position prescription lenses in front of your eyes. This guide explains single PD, dual PD, distance PD, near PD, two at-home measurement methods, and when a professional measurement is the safer choice.
Use a professionally measured PD whenever it is available. At-home measurement can be useful, especially for many single-vision orders, but accuracy varies and it is not the best choice for every prescription or lens design.
RenewLens requires the necessary PD information before lens production can be completed.
Measure in MillimetersNever enter inches
Repeat the ReadingCompare at least three measurements
Use the Correct PD TypeSingle, dual, distance, or near
Do Not GuessAsk for help when readings disagree
THE BASIC MEASUREMENT
What Is Pupillary Distance (PD)?
Binocular PD is the distance in millimeters between the centers of your pupils. Monocular or dual PD records the distance from the nose reference point to each pupil separately.
PD is not pupil size and is not a lens-power value such as sphere, cylinder, axis, prism, or ADD. It is a fitting measurement that helps position the prescribed lens design correctly in relation to your eyes.
Why Accurate PD Matters
When the optical reference points in the lenses do not align as intended, unwanted prismatic effects can occur. Whether an error is noticeable depends on lens power, lens design, the size and direction of the error, frame fit, and wearer sensitivity.
Possible symptoms may include blur, visual fatigue, eye strain, headaches, difficulty adapting, or trouble finding the clearest viewing zone. These symptoms can have other causes, so discomfort should be reviewed rather than assumed to be a PD problem.
HOW PD IS WRITTEN
Single PD vs. Dual PD
Dual or Monocular PD
31 / 32 mmTwo measurements: right eye first, then left eye, from the nose reference point to each pupil.
Dual PD preserves separate right- and left-eye measurements and can be preferable for progressives, stronger prescriptions, facial asymmetry, and designs requiring eye-specific positioning.
- If the form asks for one single/binocular PD, enter one number such as 63.
- If it has separate right and left PD fields, enter 31 right and 32 left.
- If you have dual PD and the form specifically asks for one binocular number, add them: 31 + 32 = 63.
- Do not automatically divide a single PD equally because the eyes may not be perfectly symmetrical.
THE VIEWING DISTANCE CHANGES THE MEASUREMENT
Distance PD vs. Near PD
Distance PD is measured while looking toward a distant target. Near PD is measured while focusing at a close working distance and is usually smaller because the eyes turn inward for near work.
| Lens Type | PD Commonly Requested | Other Information That May Be Needed |
|---|---|---|
| Single-Vision Distance | Distance PD | Frame and prescription compatibility |
| Single-Vision Reading | Near PD may be requested | Intended reading distance |
| Progressive Lenses | Often monocular distance PD | Fitting height and frame information may be required |
| Computer or Professional | Depends on design and working distance | Fitting height, frame data, and working range may be required |
| Prescription Sunglasses | Depends on single vision or progressive design | Frame curve and compatibility may matter |
Enter the exact type of PD requested. Do not substitute near PD for distance PD, or the reverse, unless RenewLens instructs you to do so.
What Is a Normal Adult PD?
Adult binocular PD is often around the low 60s in millimeters. Approximately 50–70 mm is a commonly reported adult range, but real measurements can fall outside it because facial anatomy varies.
Group averages differ and do not tell you what your own PD should be. Never copy an average or change your measurement simply because it looks unusual.
METHOD 1 · MEASURE BY YOURSELF
Mirror and Millimeter-Ruler Method
Use a rigid ruler marked in millimeters, a mirror at eye level, bright even lighting, and a steady head position.
1
Stand 8–12 Inches From the Mirror
Keep your face level and square to the mirror.
2
Hold the Ruler Flat and Level
Place it against your brow or forehead so it runs horizontally across the pupils.
3
Align Zero With One Pupil Center
Position the zero-millimeter mark directly above one pupil center.
4
Keep Your Gaze Straight
Look into your eyes in the mirror rather than scanning along the ruler.
5
Read the Opposite Pupil Center
The millimeter mark above the other pupil center is your binocular PD.
6
Repeat at Least Three Times
Reset the ruler each time. If results do not agree closely, do not guess.
Printable rulers can be inaccurate when a browser or printer scales the page. Confirm that any printed ruler is at 100% actual size against a known physical measurement.
METHOD 2 · HAVE SOMEONE HELP
Friend-Assisted PD Measurement
A helper can make the ruler easier to position and read. For distance PD, look past the helper at a distant target instead of at the ruler or the helper’s face.
- Sit or stand upright with your head level.
- Look at a distant object across the room.
- Have the helper keep the ruler level at your eye line.
- Align zero with one pupil center.
- Read the mark at the other pupil center.
- Repeat at least three times.
For Dual PD
Measure from the same center reference point on the nose bridge to the right pupil center, then to the left pupil center. Record the right-eye value first.
AVOID MEASUREMENT ERRORS
Common PD Measurement Mistakes
Positioning Mistakes
- Tilting the ruler or head
- Moving closer during the reading
- Holding the ruler away from the face
- Measuring from the pupil edge
- Using a flexible ruler
Data-Entry Mistakes
- Entering inches instead of millimeters
- Reversing right and left PD
- Entering near PD for distance
- Splitting single PD equally without instruction
- Using an average instead of your result
Parallax can affect ruler readings when the ruler, pupil, and observer are not aligned. Keeping the ruler close, the head still, and the gaze fixed helps reduce—but does not eliminate—this error.
WHEN DIY IS NOT THE BEST OPTION
When Should a Professional Measure Your PD?
- You are ordering progressive, bifocal, or trifocal lenses
- Your prescription is strong or differs significantly between eyes
- Your prescription includes prism
- You have strabismus or another eye-alignment condition
- You need computer, occupational, or customized measurements
- You are ordering glasses for a child
- Your home measurements do not agree closely
- Your previous glasses caused persistent blur, strain, or headaches
Progressive lenses require more than PD alone. Fitting height and additional frame or position measurements may be needed so the viewing zones align properly.
What If Your Prescription Does Not Include PD?
PD is often not printed on an eyeglass prescription because it is a dispensing measurement rather than a lens-power value. U.S. federal rules do not require PD on every prescription, although some states have additional requirements.
You can ask your eye doctor or optician whether they measured it, request a copy when available, have a professional measure it, or use the at-home methods above when appropriate.
RenewLens requires PD before producing prescription lenses. You may be able to place the order first and provide missing information afterward, but production remains on hold until the required measurement is received.
Do Not Estimate PD From Old Glasses or Population Averages
- Do not copy another person’s PD
- Do not choose the closest “normal” number
- Do not assume both monocular values are equal
- Do not reuse near PD as distance PD
- Do not enter a number you cannot reproduce consistently
INFORMATION FOR RENEWLENS ORDERS
How PD Is Used for Lens Replacement
RenewLens uses your prescription, PD, selected lens design, frame information, and any other required fitting measurements to position the lenses for your order.
Single-vision orders often use distance or near PD depending on intended use. Progressive, professional, and some computer-lens orders may require monocular PD, fitting height, and additional information. RenewLens will contact you if more measurements are needed.
Have your prescription and PD ready?
Select your replacement lenses and provide the requested information during or after checkout.
FREQUENTLY ASKED QUESTIONS
Pupillary Distance FAQs
What is a normal PD range for adults?
Adult binocular PD is often around 63 mm, and approximately 50–70 mm is a commonly reported range. Measurements can fall outside that range, so use your own verified PD.
Can I order RenewLens lenses without PD?
PD is required before lens production. You may place the order and provide it afterward, but production cannot be completed until the required PD is received.
Is dual PD better than single PD?
Dual PD preserves separate right- and left-eye measurements and can be preferable for progressives, stronger prescriptions, facial asymmetry, and eye-specific positioning.
What if I enter the wrong PD?
Contact RenewLens immediately. The information may be corrected before production begins, but changes may not be possible after production starts.
Is measuring PD at home accurate?
Home measurements can be useful, but accuracy varies by method, positioning, lighting, and the person measuring. Professional measurement remains more dependable.
Does PD need to be exact?
The precision needed depends on lens power, design, frame fit, and wearer sensitivity. Stronger and multifocal prescriptions make accurate positioning more important.
Is PD included on every eyeglass prescription?
No. U.S. federal rules do not require PD on every prescription, although some states have additional requirements.
Can I add two dual PD numbers together?
Yes, when the form asks for one binocular PD. For example, 31 mm right plus 32 mm left equals 63 mm. Keep them separate when right and left fields are provided.
Is near PD the same as distance PD?
No. Near PD is usually smaller because the eyes converge for close work.
Do progressive lenses need more than PD?
Usually, yes. Fitting height and additional frame or position information may also be required.
Can I reuse an old PD measurement?
Adult PD is generally stable after growth, but confirm whether it is distance or near PD and single or dual PD. Children and uncertain measurements should be rechecked.
Should children have PD measured professionally?
Yes. Children’s facial measurements change as they grow, so professional measurement is recommended.
MEASURE CAREFULLY · ENTER THE CORRECT PD TYPE
Ready to Order New Prescription Lenses?
Choose your lens type, upload your prescription or provide it later, and submit the PD and any additional measurements requested for your order.