How to Tell If Your New Glasses Fit Right - And Why It Matters

Do your glasses fit right?

Maybe they’re slipping on your nose more than they used to, or they’re hurting behind your ears.

Or perhaps you’ve just purchased a new pair of frames, but your vision is blurry. Surely, it’s the prescription, right?

Not necessarily. If your glasses aren’t fitting right, it could cause several problems, including distorted vision. They may even discourage you from wearing glasses altogether. Resulting in further deterioration, eye strain, fatigue etc. Read on to find out how important it is to have well-fitting glasses, and what you can do to make sure yours are sitting perfectly on your face.

What Happens If Your Glasses Don’t Fit Right?

Vision Problems

This is usually the biggest sign that something’s wrong with your glasses. We often blame the prescription, but it’s important to make sure your glasses are fitting right before changing the lenses.


Ill-fitting glasses can cause blurred or distorted vision, either at the center of your vision or along the periphery.

Man looking at his glasses concerned

Whatever may be causing the issue, it’s important to address it right away. Wearing glasses that don’t provide clear vision strains your eyes, forcing them to work harder than they should. Over time, this can lead to physical symptoms, like those listed below.



Wearing glasses that don’t fit right can lead to headaches. Often this is because the glasses are too tight. They may be pinching behind your ears, at the sides of your head, or on your nose.

Woman with headache caused by her glasses

Several hours of this can create a tension headache, which is a type of headache that feels like you have a tight band around your head.

It could also be that your eyes have to work harder to see clearly. Over the course of a few hours, that can lead to eyestrain-related headaches.



With the right-fitting glasses, your eyes don’t have to expend too much effort doing their job. If your glasses don’t fit right, though, your eyes are going to have to work harder. Eye muscles can get tired just like any other muscle in your body. When overworked, they can easily become strained.

Male massaging nose bridge suffering from eyestrain

Unfortunately, when your eyes feel fatigued, it often spreads to the rest of your body. According to the Mayo Clinic, eyestrain can make you tired and reduce your ability to concentrate.


Another common physical side effect of improperly fitted glasses is dizziness and/or vertigo. The right frame adjusted correctly will position the lenses so that your eyes look straight through the middle of them.

Glasses that don’t fit right may skew your vision so that you’re not looking through the middle of the lens, but somewhere else. Your focal point may be directed a little too high or low, or too far to one side or the other.

That means you won’t experience the corrective power of the lenses as you should, and your vision will be skewed. Your eyes may struggle to focus on the surrounding objects, and those objects may appear farther away or closer than they actually are.

Over an hour or more, that can cause you to feel dizzy or lightheaded, or may even throw you off balance.



The eyes are constantly sending signals to your brain, and your brain then interprets those signals to tell you what you’re seeing. If you’re not seeing clearly out of your ill-fitting glasses, your brain will get skewed messages about the world around you.

The brain tries to correct this misalignment by redirecting the eyes, but this stresses the eye muscles, causing them to become strained and fatigued. You may feel dizzy and that, in turn, may cause you to feel nauseated.

Red, Irritated Skin

If you notice areas of red and irritated skin where your glasses sit, that probably means they’re too tight in those areas. The nose pads may not be adjusted correctly, or the temples might be digging in behind your ears. It could also be that the frames are bent or crooked.



Are you squinting while wearing your glasses? That’s usually a sign that your eyes are struggling to see clearly. It could be your prescription, but it could also be that your glasses don’t fit right.


Signs Your Glasses Do Not Fit Right

To find out if you may be experiencing some of these side effects of improperly fitted glasses, ask yourself whether any of these symptoms sound familiar:


  • Blurry or distorted vision
  • Tension headaches later in the day
  • Sensitive areas behind the ears, at the sides of your head, or over the bridge of your nose
  • Frequent removal of glasses because something hurts
  • Glasses slide off your face when you look down, chew, or talk
  • Dizziness or lightheadedness after wearing the glasses for a while
  • A feeling of vertigo
  • Fatigue and an inability to concentrate
  • Motion sickness or nausea
  • Red areas on the bridge of the nose or behind the ears
  • Squinting


7 Factors that Affect How Your Glasses Fit


There are many individual differences in frames that can affect how they fit on your face. You may have noticed some of these differences when shopping for new glasses.  


1. Frame Width

This describes how wide the frames are from left to right. Ideally, the width should align with your face’s width at the temples, or be just slightly wider. The space between your temple and the frame should be no larger than a finger’s width.

If the frames extend too far past the sides of your face, or if your eyes aren’t centered in the middle of the lenses, the frames aren’t the right width for you.


2. Lens Width

This refers to how wide each lens is, measured in millimetres (mm). You can find this measurement on your glasses, usually on one of the temples. The lens width is the first number of three.

When you gaze through the lens, the centre of your pupil should align with the optical centre of each lens. If the lenses are too wide or too thin related to the natural distance between your eyes, the glasses probably won’t fit very well.

The size of the lenses is also essential to the proper functioning of progressive lenses. The right size will give you enough space for near, immediate, and distance zone powers from your prescription.


3. Arm Length

The armor “temple” is the piece that goes over your ear. Different frames have different lengths of arms, so you want to choose one that fits you well. Ideally, the arm should wrap comfortably around your ear without causing pain anywhere.

Though you can adjust this slightly by bending the end of the arm, it’s best if the basic frame isn’t too far off your natural size.

The arm or temple length measurement can also be found on your glasses. It is the last number of the three printed on the temple piece.


4. Bridge Width

This refers to the width of the eyeglasses frames at the bridge—the part that fits on your hose. If this width is too narrow for you, it’s going to pinch, feel tight, and leave red marks behind.

If it’s too wide, it’s going to slide down your nose or even fall off.
The bridge width is the second number printed on the temple of your eyeglass frames.


5. Pupillary Distance

How far is the distance between the pupils of your eyes? You may have had a technician use a machine that looks a little like binoculars to check this. It helps them to center the frames in front of your eyes.

This distance is a factor when you’re shopping for glasses, as you want frames that easily accommodate it. Then you’ll be able to look straight through the middle of each lens to achieve optimal vision. If the fit is off, you’ll end up looking out of the sides instead, which will make your vision blurry.


Download your free pupillary distance ruler here!


6. Nose Pads

Plastic frames usually sit directly on top of the bridge of your nose, but metal frames rest on nose pads.


These pads need to be adjusted properly to fit well. If they're not, you'll notice pinching or slipping, and your glasses may hurt after wearing them for a couple of hours.


7. Your Face and Head Size

Is your face of average size, or do you find yourself regularly gravitating toward smaller or larger frames? Keep this in mind when shopping for glasses.

When everything is working right, the frame should sit in the middle of your face, no higher than your eyebrows, and the total width should match the width of your face.


When you wear the glasses, they should give your appearance a sense of overall balance.


4 Ways To Test How Your Glasses Are Fitting

Now that you know how glasses are supposed to fit, how can you tell if your glasses are fitting correctly?

Start by asking yourself whether you may be experiencing any of the negative side effects of ill-fitting glasses. Then check for the following.


1. How’s Your Vision?

Can you see clearly out of your glasses? If not, check the fit of your frames. Do that before you blame the prescription. Once you get the fit correct, if the vision is still blurry, give your eyes a couple of days to adjust. Then check with your optometrist.


2. Do the Glasses Feel Tight Or Loose?

You want your glasses to stay in place, but you don’t want them to be so tight that they cause headaches. On the other hand, you don’t want them so loose that you’re constantly having to push them back into place.

Ideally, they shouldn’t feel uncomfortably tight and you should be able to go through your day without thinking about them. If you forget they’re on your face, that’s a good sign!

3. Does the Size Seem Right?

It might be nice if we had sizes for glasses like we have sizes for most other items we wear, like shoes, pants, and shirts.

Glass frames do have sizes, but most of us are unfamiliar with them and don’t understand where to find sizing information. As we explained in this post, glass frames are measured in three main aspects:

  • lens width
  • bridge width (distance between lenses to be exact)
  • temple length

These numbers are labeled on the interior of the frame, usually on one of the temple tips.

Once you know more about sizes, you’ll become familiar with which ones work best for you. This is particularly important when buying frames online.

But these numbers are just a guide, fit of a frame isn't solely determined on whether or not you have a 18mm bridge or a lens width of 48mm.

Primarily you can tell if your glasses are too big or too small by how they feel. Glasses that are too big will frequently slip off your face and ears, or the vision won’t be clear because the lenses extend too far past the sides of your face.

Glasses that are too small will feel too tight against the sides of your head, above your ears, or behind your ears. You may also feel too much pressure on the bridge of your nose.


The vision may not be quite right because your eyes are looking out the sides of the lenses rather than through the center.

We love this video from "That Glasses Guy" on YouTube, he does a fantastic job of explaining what to look for when shopping for that perfect fitting pair of glasses.



4. Do the Glasses Sit Evenly On Your Face?

Well-fitting glasses sit straight on your face. If your glasses are crooked or tilted, they'll not only look skewed, but your vision will probably be skewed too. Plus, crooked frames could cause tightness on one side and looseness on the other.

Here’s a tip: don’t judge the evenness of your glasses by checking them against your eyebrows.


People often have eyebrows or ears that may be on slightly different levels. Instead, check where they sit relative to the bottoms of your eyes. You’ll be better able to tell that way if they are straight on your face.  


How Often Do I Need to Adjust the Fit of My Glasses?

How often you have to adjust your glasses depends on your lifestyle and also the quality of your eyewear. If you often take your glasses on and off throughout the day, they’re more likely to get bent and may require more frequent adjustments.

Likewise, if you’re very active and wearing your glasses under a helmet or while engaged in sports, you may need to frequently check to be sure your glasses are still fitting right.

Better quality frames generally are made from thicker, higher quality materials which in turn usually hold their shape better - compared to chepaer alternatives.

On the other hand, if you put your glasses on in the morning, go to work in an office, and take them off at the end of the day, the fit will last longer for you.

In general, it’s best to check the fit of your glasses once a year unless you're experiencing problems. Then feel free to get them adjusted more often. Most eyeglass stores will adjust your glasses for a small fee or even for free.


Hopefully you found this article helpful. Please check out our other eyecare blogs. Thanks for stopping by.





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