Glasses Frame Guide: Face Shapes, Frame Sizes, Materials and Fit

Frames are the part of your glasses that everyone sees, so it is natural to choose them mainly on looks. Yet a frame also decides how comfortable your glasses feel at the end of a long day, whether they slide down your nose, how thick your lenses will be and even how well you see through progressive lenses. A beautiful frame that fits badly will end up in a drawer.

This guide brings together style and function. You will learn how face shape can guide your choice, how to read the three numbers printed on the inside of every frame, the pros and cons of common frame materials, and a step-by-step fit check you can do in the shop or at home. If you are curious about which shapes might flatter you, try our face shape tool before you start browsing.

Start with your face shape

Opticians and stylists often group faces into a few basic shapes. Most people are a mix, and these suggestions are guidelines rather than rules. The general principle is contrast: angular frames soften round faces, and curved frames soften angular ones. Frames should also roughly follow the line of your eyebrows and be about as wide as the widest part of your face. Our article on choosing frames for your face shape includes more examples.

Beyond face shape

Colour and proportion matter just as much as shape. Warm skin tones often suit tortoiseshell, honey, olive and gold; cool tones often suit black, grey, silver, blue and crystal frames. Thick, dark frames make a strong statement on a small face, while thin metal frames can look understated on large features. Consider your hairstyle, your work environment and the fact that you will wear these glasses every day. If in doubt, take photos of yourself in a few frames and compare them later.

Understanding frame measurements

Look on the inside of the temple arm or the bridge of any frame and you will see a set of numbers, usually something like 52□18 140. These are the boxing measurements in millimetres.

Lens width (eye size)

The first number, often between about 40 and 60 mm, is the horizontal width of one lens. It is the most important number for overall frame size. A small adult face may suit 48 to 50 mm, an average face 51 to 54 mm, and a broad face 55 mm and above, but bridge width and frame shape also affect the overall width.

Bridge width

The second number, usually 14 to 24 mm, is the distance between the two lenses at their closest point. It determines how the frame sits on your nose. Too narrow and the frame pinches or sits too high; too wide and it slips down.

Temple length

The third number, usually 135 to 150 mm, is the length of the arm from the hinge to the tip. The temple should be long enough to curve down comfortably behind your ear without pressing.

Lens height and total frame width

Some retailers also list lens height (the vertical depth of the lens) and total frame width. Lens height matters for multifocals: progressive lenses usually need enough height below the pupil to fit the reading zone. Total frame width should be close to the width of your face at the temples. If you have a pair of glasses that fits well, copying its measurements is the easiest way to buy new frames, especially online.

Frame styles and constructions

• Full-rim: the rim surrounds the whole lens. It is the most durable option, hides thick lens edges and suits any prescription.
• Semi-rimless (half-rim): the rim runs along the top; the bottom of the lens is held by a thin nylon cord. Light and discreet, but the exposed edge can chip and thick edges are visible.
• Rimless (drilled): lenses are attached directly to the bridge and temples with screws or plugs. Extremely light and minimal, but less robust, and they need impact-resistant lens materials such as Trivex, polycarbonate or 1.60 index.
• Browline: a bold upper rim with a thin metal lower rim, a classic retro look.
• Wrap and sports frames: curved frames that follow the face for protection and peripheral vision; high prescriptions may be limited in strongly curved frames.

Frame materials

Acetate (cellulose acetate)

Acetate is a plant-based plastic made from cellulose and the most common material for plastic frames. It comes in a vast range of colours, layers and patterns, including tortoiseshell. Opticians can heat and adjust it to your face. It is slightly heavier than some alternatives and can become brittle or lose its shape over years, especially with heat exposure. High-quality acetate frames usually have metal cores in the temples for strength.

Injected plastics and TR90

Cheaper plastic frames are often injection-moulded from various polymers. TR90 is a specific thermoplastic nylon material known for being very light, flexible and resistant to breaking. It bends rather than snaps, making it excellent for children, sports and active adults. It is less easy to adjust precisely than acetate or metal, and colour options can look less rich.

Metal frames: stainless steel, monel and titanium

Stainless steel frames are strong, thin, corrosion resistant and affordable. Monel, a nickel-copper alloy, is widely used and easy to shape but contains nickel, which can cause skin allergy in some people. Titanium is strong, very light, corrosion resistant and hypoallergenic, making it ideal for people with sensitive skin or nickel allergy. It is more expensive and harder to repair. Beta titanium and memory alloys add flexibility, allowing frames to spring back after bending.

Other materials

Aluminium frames are light and modern-looking. Wood, horn and bamboo offer a natural aesthetic but need more care and are less adjustable. Carbon fibre is light and stiff, often used in sports or combined with metal.

Matching the frame to your lenses

Frames and lenses work as a system. Before falling in love with a frame, consider your prescription:

• Strong minus (myopic) prescriptions: choose smaller, rounder or oval frames with a lens width that keeps your eyes near the centre. Thick plastic rims hide edge thickness better than rimless designs. High-index materials help; see lens materials and index.
• Strong plus (hyperopic) prescriptions: smaller frames reduce centre thickness and magnification. Aspheric lenses help.
• Progressive or bifocal lenses: make sure the lens height is sufficient, often at least around 28 to 30 mm overall for comfortable standard designs. Very narrow or steeply upswept cat-eye frames may cut off the reading area. Read more in our page on lens types.
• High astigmatism: a well-fitted frame that sits stably and does not rotate on the face keeps the lens axis aligned.

Step-by-step fit check

1. Eye position: looking straight ahead, your pupils should sit roughly in the centre of each lens horizontally, and slightly above the vertical centre for most frames.
2. Width: the frame front should be roughly as wide as your face at the temples, with no gap of more than a finger between the temple arms and the sides of your head, and no pressure on the sides.
3. Bridge: the frame should rest evenly on the nose, without pinching or leaving deep marks. Adjustable nose pads on metal frames allow fine tuning; plastic frames need the right bridge shape from the start.
4. Eyebrows: the top of the frame should roughly follow the eyebrow line, not sit far above or hide the brows.
5. Cheeks: the frame should not rest on your cheeks or lift when you smile.
6. Temples and ears: the arms should run straight back and bend just behind the top of the ear, hugging gently without pressure.
7. Movement test: look down and gently shake your head. Well-fitted glasses stay in place.
8. Eyelashes: lenses should not touch your lashes when you blink.

Special situations

Children

Children need flexible, durable frames, often TR90 or silicone, with spring hinges, a good bridge fit for a developing nose and sometimes cable temples or straps for toddlers. Lenses should always be polycarbonate or Trivex.

Sports and work

Ordinary frames are not designed to protect the eyes from impact. For racket sports, ball games, workshop and industrial work, choose frames certified to protective standards with impact-resistant lenses.

Sensitive skin and allergies

Red, itchy patches where the frame touches the skin may indicate a nickel allergy or sensitivity to certain plastics. Titanium, high-quality acetate and hypoallergenic nose pads usually help.

When to see an eye care professional

Frame fit problems are usually solved by an optician. However, see an optometrist or doctor if new glasses cause persistent headaches, double vision or dizziness after a reasonable adaptation period, as the prescription or lens centration may need to be checked.