Sunglasses Size Calculator
Enter your face width and bridge preference to find the ideal sunglasses lens width, recommended bridge size, and temple length. You also get the total frame width, a fit verdict comparing your face to the frame, and a size category. Switch between millimetres and inches - all results update instantly.
How sunglasses sizing works
Every pair of sunglasses carries a three-number size code stamped inside the temple arm, for example 55-18-140. The first number is the lens width in millimetres, measured horizontally at the widest point of one lens. The second is the bridge width, the gap between the inner edges of the two lenses where the frame rests on your nose. The third is the temple length, measured from the hinge all the way to the tip of the arm, including the curved section that hooks behind your ear. Knowing these three numbers - and how they relate to your face - is the fastest way to shop online without trying frames on.
How to measure your face for sunglasses
You need one measurement: your face width. Hold a soft tape measure or a ruler firmly against your face and measure temple to temple, at the level of your eyes and just above your cheekbones. Most adults fall between 120 mm and 160 mm. Your ideal total frame front width (the combined span of both lenses plus the bridge) should sit within about 0-4 mm wider than your face for a natural fit, or 5-8 mm wider for a relaxed or oversized look. Once you have your face width, this calculator works out the matching lens width using the formula: lens width = (target frame width - bridge width) / 2. The temple length is estimated from your face width: narrower faces need shorter arms (around 130-135 mm) and wider faces need longer arms (around 145-150 mm) to reach comfortably behind the ear.
Choosing the right bridge width
Bridge width is often overlooked but matters as much as lens width for comfort. A bridge that is too narrow will pinch; one that is too wide lets the frames slide down. If you have a low nose bridge, narrow-set eyes, or a narrow nose, look for a bridge of 14-17 mm. If you have a higher or wider nose, or widely spaced eyes, a bridge of 18-24 mm keeps the frame sitting high and centred. The inner padding of nose pads (common on metal frames) can also compensate a few millimetres in either direction.
Face shape and frame style guide
Face shape influences which frame silhouette flatters you most, though personal preference always wins. Oval faces are versatile - almost any frame works. Round faces benefit from angular styles (square, rectangular, or geometric lenses) that add definition and length. Square faces suit rounder or oval frames that soften strong jaw lines. Heart-shaped faces (wider forehead, narrower chin) look balanced in frames wider at the bottom, rimless designs, or lightweight acetate. Oblong or rectangular faces suit taller lenses and oversized styles that add visual width. Diamond faces, with high cheekbones and a narrower forehead and chin, complement oval or cat-eye frames. These are guidelines, not rules - the best sunglasses are the ones you feel good wearing.
Sunglasses size categories by lens width
| Size | Lens width | Bridge width | Temple length | Typical face width |
|---|---|---|---|---|
| Small | 47-52 mm | 14-17 mm | 130-135 mm | Under 129 mm |
| Medium | 53-55 mm | 16-19 mm | 135-140 mm | 129-139 mm |
| Large | 56-60 mm | 18-21 mm | 140-145 mm | 139-149 mm |
| Oversized | 61 mm+ | 20-24 mm | 145-150 mm | Over 149 mm |
Standard size bands used across major eyewear brands. Bridge width and temple length ranges are typical defaults - individual frames vary.
Frequently asked questions
What do the three numbers on sunglasses mean?
The three-number code stamped inside the temple arm (for example 55-18-140) gives the lens width, bridge width, and temple length, all in millimetres. Lens width is the horizontal span of one lens at its widest. Bridge width is the nose gap between lenses. Temple length runs from the hinge to the tip of the arm, including the bend that hooks behind your ear.
How do I find my sunglasses size without trying them on?
Measure your face width temple to temple with a ruler or tape measure. Your ideal total frame width (lens x 2 + bridge) should be 0-4 mm wider than your face for a standard fit. This calculator works out the lens width from your face width and chosen bridge size, so you can search for frames by that three-number code.
What is the difference between lens width and frame width?
Lens width is the size of one lens measured horizontally at its widest point. Total frame width (also called front width) spans both lenses and the bridge: approximately (lens width x 2) + bridge width. This is the number to compare against your face width when checking fit. Some brands include end-piece width in the total, adding a few millimetres.
How do I know if my bridge width is correct?
A correct bridge width leaves the frame sitting level on your nose with the lenses centred over your eyes. If the frames slide down or gap away from your face, the bridge is too wide. If they pinch or leave red marks, the bridge is too narrow. Most adults sit in the 16-20 mm range, with narrower bridges suiting low or narrow nose bridges and wider ones suiting higher or broader noses.
Does the frame size code work the same for all brands?
The three-number system (lens-bridge-temple in mm) is a widely used industry standard, but a few brands measure lens width differently or include end-piece width in their total. Use the code as a close starting point, and check that the total front width matches your face width before buying.
What sunglasses size suits a wide face?
For a face width over about 145 mm, look for a lens width of 57-62 mm, a bridge of 18-22 mm, and temples of 145-150 mm. These dimensions give a large or oversized frame that spans the face comfortably without the frame ends digging into the temples.