# Sunglasses Size Calculator

URL: https://speedycalculator.com/calculators/everyday-life/sunglasses-size/
Last updated: 2026-10-25

> The sunglasses size calculator estimates the frame width and lens size (small, medium or large) that fit your face, and your face shape from forehead, cheekbone, jaw and face-length measurements, with frame shapes that suit it.

## Inputs

- Face width at temples (mm, cm, in)
- Bridge width (mm)
- Forehead width (cm, in, mm, m)
- Cheekbone width (cm, in, mm, m)
- Jawline width (cm, in, mm, m)
- Face length (cm, in, mm, m)

## Results

- Ideal lens width
- Lens size
- Typical temple (arm) length
- Estimated face shape

## Formula

```
Frame width ≈ face width at the temples
Lens width ≈ (frame width − bridge − 2 × 5 mm hinges) ÷ 2
Lens size: small < 52 mm, medium 52–55 mm, large 55–58 mm, extra large > 58 mm
```

## Explanation

Glasses are labelled with three numbers like 52-18-140: lens width, bridge width and temple (arm) length in millimetres. A good fit has the frame about as wide as your face at the temples, with your eyes near the centre of each lens. Face shape guides style: angular frames balance round faces, round frames soften square ones.

### How to use the Sunglasses Size Calculator

- **Face width at temples**
- **Bridge width**
- **Forehead width**
- **Cheekbone width**
- **Jawline width**
- **Face length**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Measure across your forehead, across the widest part of your cheekbones, along your jawline and from hairline to chin, and your face width at the temples.

### Frames by face shape

Face shapeFrames that suitOvalAlmost any – try oversized or geometricRoundRectangular, square or angular framesSquareRound, oval or aviator framesHeartBottom-heavy, round or rimless framesDiamondCat-eye, oval or rimless framesOblongTall, wide or oversized frames

### Tips

- Measure over thin clothing with a soft tape held snug but not tight, and keep the tape level all the way round.
- Take each measurement twice; if you are between sizes, the larger size is usually the safer choice.
- Size charts vary by brand and country – check the maker's own chart when it is available.
- For sewing projects, pre-wash fabric before cutting and buy 10% extra for shrinkage, pattern matching and mistakes.

### Common mistakes to avoid

- Mixing inches and centimetres between the tape and the size chart.
- Forgetting seam and hem allowances when cutting fabric.
- Measuring an old, stretched garment instead of your body.

### Inputs explained

FieldWhat to enterFace width at templesUnits: mm, cm, inBridge widthUnits: mmForehead widthUnits: cm, in, mm, mCheekbone widthUnits: cm, in, mm, mJawline widthUnits: cm, in, mm, mFace lengthUnits: cm, in, mm, m

### What each result means

- **Ideal lens width** = ([Face width at temples] - [Bridge width] - 0.01)÷2
- **Typical temple (arm) length** = clamp([Face width at temples]×1.05, 0.135, 0.15)

## Worked example

Inputs — Face width at temples: 135 mm; Bridge width: 18 mm; Forehead width: 13 cm; Cheekbone width: 13.5 cm; Jawline width: 12 cm; Face length: 19 cm.

Results — **Ideal lens width = 54 mm**; Lens size = Medium; Typical temple (arm) length = 142 mm; Estimated face shape = Oval.

## FAQ

**What do the numbers on glasses mean?**
Lens width, bridge width and temple length in mm – for example 52-18-140.

**How do I know if sunglasses are too big?**
Your eyes should sit near the centre of the lenses and the frame shouldn't extend far beyond the sides of your face.

**Which sunglasses suit a round face?**
Angular or rectangular frames that add definition.

**What formula does the Sunglasses Size Calculator use?**
Frame width ≈ face width at the temples.