Finding reading glasses you love is one thing. Finding reading glasses that actually fit is another.
A frame can look fantastic online, but if it constantly slides down your nose, feels tight at the temples or sits awkwardly on your face, you're probably not going to enjoy wearing it.
The good news is that choosing the right size online is easier once you understand the numbers.
This reading glasses size guide explains frame width, lens width, bridge width and temple length, plus an easy way to compare a new pair with glasses you already know fit well.
The easiest way to find your reading-glasses size is to start with a pair you already own that fits well. Check the numbers inside the temple arm - usually lens width, bridge width and temple length - then compare them with the measurements of the frames you're considering. Overall frame width is particularly useful when comparing how wide different glasses will feel on your face.
What Do Reading Glasses Sizes Mean?
Glasses are usually measured in millimetres.
You may have noticed a series of numbers printed inside the temple arm of glasses you already own. They might look something like:
51 – 20 – 145
These numbers generally refer to:
- 51 mm — Lens width
- 20 mm — Bridge width
- 145 mm — Temple length
You'll also sometimes see an overall frame width listed separately.
That measurement can be particularly useful when shopping online because it gives you an indication of how wide the entire frame will be across your face.
The Four Reading Glasses Measurements Worth Checking
1. Overall Frame Width
This is the measurement across the entire front of the glasses.
If glasses regularly feel too wide or extend well beyond the sides of your face, compare the overall width with a pair you already own.
Likewise, if glasses tend to feel tight at your temples, look at how the overall width compares with a comfortable pair.
This is one reason we don't recommend relying solely on descriptions such as small, medium or large. Actual measurements are much more useful.
If standard frames are regularly too wide for you, see our Reading Glasses for Small Faces Guide.
2. Lens Width
Lens width is the horizontal width of one lens at its widest point.
It's usually the first number in the three-number measurement printed inside a pair of glasses.
For example:
51 – 20 – 145
The 51 indicates a lens width of approximately 51 mm.
Lens width can help you compare the proportions of different frames, but don't use it by itself to determine whether a pair will fit.
Two frames with the same lens width can have quite different overall dimensions because of their bridge, hinges and frame design.
3. Bridge Width
Bridge width is the distance between the two lenses, across the section that sits on your nose.
In our example:
51 – 20 – 145
the 20 is the bridge measurement.
If the bridge doesn't work well with your nose, glasses may feel loose, sit differently from where you'd like them to, or simply feel uncomfortable.
Again, measurements are a guide rather than a guarantee. The design and shape of the bridge also affect how a particular frame sits.
4. Temple Length
The temples are the arms extending from the front of the glasses and over your ears.
The final number generally represents their length.
So:
51 – 20 – 145
means a temple length of approximately 145 mm.
If the arms on your current glasses feel particularly long or short, comparing temple measurements can help when you're considering another pair.
Ready to compare? Browse our reading glasses and check the measurements listed on each style against a pair you already know fits well.
The Easiest Way to Find Your Reading Glasses Size
You don't necessarily need to measure your face.
Instead, find a pair of glasses or sunglasses you already own that fits you really well.
Then:
- Look inside the temple arm for the measurements.
- Check the overall frame width if you can.
- Compare those measurements with the glasses you're considering.
- Look at the shape and proportions as well as the numbers.
You don't need to find another frame with identical measurements.
You're simply giving yourself a useful reference point.
If your favourite pair is approximately 138 mm wide, for example, and another frame is substantially wider, you'll know to expect a noticeably different look and fit.
Does Lens Width Tell You the Overall Size of Glasses?
Not necessarily.
This is an important distinction when buying reading glasses online.
A smaller lens measurement does not automatically mean a smaller overall frame.
The bridge, hinges, frame thickness and shape all contribute to the total width.
That's why we recommend looking at as many measurements as are available rather than deciding that a frame is "small" simply because it has a relatively narrow lens.
Small vs Medium vs Large Reading Glasses
You'll sometimes see reading glasses described as small, medium or large.
These descriptions can be useful for quickly comparing frames within the same range, but there isn't one universal measurement that makes every pair of glasses "small" or "large".
A chunky square frame and a slim rectangular frame can feel completely different even if some of their measurements are similar.
Rather than getting too caught up in size labels, concentrate on:
- Overall frame width
- Lens width
- Bridge width
- Temple length
- Frame shape
- How those measurements compare with glasses that already fit you
That's much more useful than assuming you're always a particular glasses "size".
How Should Reading Glasses Fit?
A good pair of reading glasses should feel comfortable and reasonably secure.
Look at how the frame sits when you're wearing it.
Ideally:
- The glasses shouldn't continually slide down your nose.
- The temples shouldn't feel uncomfortably tight.
- The frame shouldn't feel excessively loose.
- The arms should sit comfortably around your ears.
- The glasses should sit where you want them without constant adjustment.
Most importantly, you should like how they look.
Fit matters, but reading glasses are also sitting right in the middle of your face. There's no reason they can't be functional and something you're excited to wear.
Should Reading Glasses Match Your Face Shape?
You don't need to choose reading glasses according to rigid face-shape rules.
You've probably seen advice saying:
Round faces should wear square glasses.
Square faces should wear round glasses.
We prefer to treat those ideas as inspiration rather than rules.
Frame proportion is much more useful when you're thinking about size and fit.
A small face can wear bold glasses. A round face can wear round glasses. An oval face doesn't automatically suit everything.
Choose the shape you like, then look at whether the proportions and measurements work for you.
Can You Wear Oversized Reading Glasses?
Absolutely.
There's a difference between glasses that are intentionally oversized and glasses that simply don't fit.
Oversized readers are a style choice. They can be bold, interesting and deliberately substantial.
But if your glasses continually fall down, feel unstable or are uncomfortable, that's a fit issue rather than an oversized aesthetic.
If you love statement frames, don't assume you need to choose something tiny simply because you have a smaller face.
Look for bold design in proportions that work for you.
Small, classic or statement-making — find the frame proportions and style that work for you.
Common Reading Glasses Sizing Mistakes
Looking Only at Lens Width
Lens width is useful, but it doesn't tell you the total width of the glasses.
Check the overall dimensions where possible.
Assuming Your Face Is Always "Small", "Medium" or "Large"
Different frame shapes fit differently.
Use size categories as a guide, not an absolute rule.
Buying Based Only on Appearance
We understand this one.
Sometimes you see a frame and immediately want it.
But spend another minute checking the measurements before hitting Add to Cart.
Assuming Bigger Means Poor Fit
Not necessarily.
If you're deliberately choosing an oversized style and it sits securely and comfortably, the extra size may be exactly what you want.
Ignoring a Pair You Already Own
Your existing glasses are one of your best sizing tools.
If they fit beautifully, use their measurements as your benchmark.
What If Reading Glasses Are Always Too Big?
If standard adult reading glasses regularly feel too wide, you may simply have a smaller or narrower face.
Look for frames with more compact overall proportions and compare them with glasses that already fit.
And remember: small-face reading glasses don't need to look small or boring.
You can still choose colour, tortoiseshell, clear acetate, geometric shapes and statement designs.
See our Best Reading Glasses for Small Faces in Australia guide for more help.
Does Frame Material Affect Fit?
Material isn't a substitute for choosing the right dimensions, but it does influence how a pair of glasses looks and feels.
Ministry of Sight specialises in acetate reading glasses, a material we love for its depth of colour, finish and ability to create distinctive frame shapes.
If you're interested in the difference between common frame materials, read our Acetate vs Plastic Reading Glasses Guide.
Buying Reading Glasses Online: Your Quick Size Check
Before buying your next pair, check:
✓ Overall frame width
How does it compare with glasses you already own?
✓ Lens width
Is the lens proportion similar to styles you like wearing?
✓ Bridge width
How does it compare with a comfortable existing pair?
✓ Temple length
Are the arms considerably longer or shorter than your current glasses?
✓ Shape
Do you actually like the proportions on your face?
✓ Style
Most importantly: are you going to want to wear them?
Measurements help you narrow the field.
Style chooses the winner.
Don't worry about matching every measurement exactly. A few millimetres' difference doesn't automatically mean a frame won't fit - shape, bridge design and overall proportions matter too. Use the measurements to compare frames rather than treating them as rigid rules.
Looking beyond fit? Our Best Reading Glasses Australia guide explains what else to consider when comparing readers, including frame materials, construction, lenses, price and overall value.
Frequently Asked Questions
What do the numbers on reading glasses frames mean?
A three-number measurement such as 51–20–145 generally refers to lens width, bridge width and temple length, measured in millimetres.
Where can I find my glasses size?
Look inside the temple arm of a pair you already own. Many glasses have their measurements printed on the inside.
How do I know if reading glasses are too wide?
If the frame feels excessively loose, extends much further beyond your face than you want or continually shifts position, compare its overall width with a pair that fits you well.
Is lens width the same as frame width?
No. Lens width measures one lens. Overall frame width measures across the entire front of the glasses. A relatively small lens measurement doesn't necessarily mean the glasses have a narrow overall frame.
What size reading glasses do I need for a small face?
There isn't one universal measurement for a small face. Compare the overall frame width, bridge and temple measurements with a pair you already know fits comfortably. Our Reading Glasses for Small Faces Guide goes into this in more detail.
Do reading glasses have to match my face shape?
No. Face-shape advice can provide inspiration, but it isn't a rule. Concentrate on fit, proportions and the styles you actually enjoy wearing.
Find Reading Glasses That Fit Your Style
The numbers matter - but they aren't the whole story.
Use frame measurements to understand how one pair compares with another. Start with glasses you already own and know fit well, then compare the frame width, lens width, bridge and temple length.
Once you've narrowed down the fit, choose the pair you actually want to wear.
Because reading glasses shouldn't just fit your face.
They should fit your style.
