How to Measure Sunglasses Size: A Comprehensive Guide
How to Measure Sunglasses Size: A Comprehensive Guide

How to Measure Sunglasses Size: A Comprehensive Guide

Discover how to measure sunglasses to find the perfect fit for your face. Measure lens width, bridge width, and temple length, or use the credit card trick to determine your ideal size.

How to Measure Sunglasses Size: A Comprehensive Guide

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Finding the perfect pair of sunglasses requires striking a balance between style and fit. It’s often a challenging endeavor. Luckily, Melonz makes it as easy as possible, with every style available in every size. However, you still need to know which size suits you best, especially when choosing multiple styles. This guide will equip you with the knowledge to measure your sunglasses size accurately, ensuring you choose a pair that delivers both comfort and a stylish look that will serve you well.

Understanding Sunglass Measurements

Sunglass measurements are typically denoted in millimeters (mm) and encompass three key dimensions:

  • Lens Width: This refers to the horizontal distance across a single lens, measured at its widest point.
  • Bridge Width: This signifies the horizontal distance between the two lenses, measured at the narrowest point on the bridge.
  • Temple Length: This represents the length of the arm that rests on your ear, measured from the hinge to the tip of the temple arm.

Measuring Your Existing Sunglasses

If you own a pair of sunglasses that fit you perfectly, this process is of course a bit simpler. Using these as a model is one of the easiest methods for determining your ideal size. Simply utilize a ruler to measure the lens width, bridge width, and temple length as described above. And there you have it, your ideal sunglasses size. 

Techniques for Measuring Your Face Size

Another way to go about determining your optimal sunglasses sizing is to measure your face. But how exactly does one accomplish that? Here are two methods to estimate your ideal sunglasses size by measuring your face:

Ruler Method:

  • Lens Width: Place the ruler horizontally across your face, just below your eyes. Align the zero mark with the bridge of your nose. The distance from the zero mark to the outer edge of your eye socket provides an estimate of your ideal lens width.
  • Bridge Width: Pinch the bridge of your nose to locate the narrowest point between your eyes. Here, measure the distance between your pupils using the ruler. Subtract 3mm from this measurement to identify your bridge width.
  • Temple Length: Accurately measuring temple length without a reference pair presents a slight challenge. However, as a general guideline, most adult temple lengths fall within the range of 120mm to 150mm.

The Credit Card Trick

This method leverages the standard width of a credit card, which is around 54mm, as a reference point to approximate your head size and, consequently, your ideal frame size. Here's how the credit card trick works:

  1. Card Placement: Position the credit card vertically in the center of your nose. This spot acts as a symmetrical reference point on your face.
  2. Head Size: Observe where the card reaches in relation to the outer corner of your eye. Based on this alignment, you can assess your head size category: small (card extends past your eye), medium (card aligns with your eye), or large-XL (card falls short of your eye).
  3. Frame Size: The distance the credit card covers provides a starting point for your ideal frame size. This estimation is further refined by adding an approximate distance to account for the space between your eye and ear.

Utilizing Sizing Charts

Once you have a rough estimate of your measurements, many sunglass retailers, including Melonz, offer sizing charts that translate lens width into recommended frame size, whether it’s small, medium, or large-XL sunglasses.

While these methods offer valuable insights, they serve as guidelines. The ultimate way to guarantee a perfect fit is to try on various sizes whenever possible. Pay close attention to how the sunglasses rest on your face—they should sit comfortably without slipping or pinching, and the lenses should provide adequate coverage without feeling excessively wide.


With the knowledge of measuring sunglasses size and the bonus credit card trick, you're well on your way to finding the ideal set of shades. Now you get to experience sunglasses that offer both comfort and undeniable style, ensuring your eyes are protected throughout the day.