Full disclaimer: I have a very bad fashion sense. I don't know how to dress well, or the right combination. Plus I am ugly. With that being said, I do know one thing. I know how to do my research before buying a product. Sunglasses were not my thing. Not even a couple of months ago. Until the day, a pair of sunglasses saved me from inevitable headache.

I have a trouble since childhood. If I stay even ten minutes under the sun, I get headache for the rest of the day. But as I live in a country that's mostly sunny (even in winter). I spend a lot of time with headache. Until the day I used a sunglass during my outdoor tour one day and was surprised to find out I didn't have a headache. I tested it several times and found out that sunglasses gave me a lot more comfort under the sun than usual. Hence, they became my regular accessory. I usually study any product before buying, and previously wrote about my experience with Air conditioners and Washing machines. I did the same type of research before buying sunglasses. I will try to write about what I learned through reading and experience.

Price and brand:

Sunglasses, like any other fashion accessory, can range from $3 to $3000 or even higher. Like many other products in the same category, expensive doesn't always mean better product. Brands definitely maintain their quality. But the question you might ask yourself before buying an expensive one is: Is this really worth it?

You might also watch this video: Sticker shock: Why are glasses so expensive?

I usually go for brands that aren't hyped or over expensive, Instead provides value for money.

How to know if a sunglass fits your face?

All sunglasses come with three numbers written on their temple (the part that rests on your ears). This is standard for all good sunglasses (If you don't see the numbers written on the sunglass temple, the glasses aren't probably good or the measurements were probably written with product specs)

The numbers are usually in the following order Lens width followed by a and then bridge width followed by a - and then temple length. Sometimes the order or format might be different, but you can easily identify them from their range. The numbers might be something like: 50□21-145 .sometimes only two numbers are written (lens and bridge), They are not hard to find if you carefully observe. These three numbers tell a lot about the measurements of a sunglass. All these measurements are in Millimetres, even the American ones.  

Size measurements on Merry's Wayfarer, and Fastrack Aviators.

The first number (ranges from 30 to 70):

The very first number (usually) in the series, that's usually at the left side of the , is the lens width in millimetres.

The second number (ranges from 10 to 30):

The second number, that usually sits right after the square (smallest number in the series) is the bridge length. Bridge is the part that connects the two lenses together and sits on your nose. Comfortable bridge length usually depends on the width of your nose and type of sunglass.

The largest number (usually ranges from 100 to 200):

The largest number in the series is the temple length. The two long part of a sunglass that sits on the ears. This number determines how far the sunglass will reach on the back of your head. What you need depends on how big your head is, and how long your hairs are.

Total sunglass width:

Total sunglass width is usually lens width*2+bridge width, but every other real life numbers, actual width often varies from the overall sum. But the sum usually gets too close. It's easy to get a reference number for future use though.

Choosing the right size:

The three numbers vary from person to person. The best way to know what fits you best is to try out few from a physical sunglass shop. Once determined, the size will work as reference for future purchases.You don't need to buy the exact numbers each time, you just need numbers very close to your reference value. But there's a catch: A number combination right for you will only work on one particular style of sunglass. The reference size for wayfarer sunglasses will not work for aviators.

You can learn all about sizes from the Ray-Ban size guide.

Frame material:

Most common frame material for sunglasses are usually plastic and metal. One material isn't necessary better than other though. Plastic sunglasses are lighter, flexible and usually more comfortable to wear. However, out of two plastic finishes (glossy and matte) I prefer the glossy finish. They just feel less brittle than the matte ones.

Metal frames are usually heavier and strong. At the end of the day though, it comes down to personal preference.  

Types of sunglass:

Well, that's going to be a very long list. There are just too many. But usually popular ones are Wayfarer, Aviators, Rounds etc. Many people usually refer to face shape while choosing sunglass type. But I've seen people going the opposite and still look good. The main idea is trial and error.

All about Sunglass lenses:

Lens plays the biggest role in sunglasses. They are the most active and useful part. Most lenses are now made of good plastic. Glass lenses are also popular though. Glass is heavy but strong. Plastic is light but extremely scratch and prone to physical damage.

Most sunglass lenses provide good UV protection (The most important functional requirement). Even the cheaper sunglasses usually come with lenses that provide full UV protection. Here's a video that explains it.

Polarized lenses are great for protection and removing reflection. It increases clarity dramatically if you are hiking, driving or fishing. But it gets hard to use a phone or pilot an aircraft. Pilots don't wear polarized glasses.

Lens colour and finish comes down to individual choice. I prefer pure gray lenses that doesn't add any extra colour. Some people prefer green, blue, red brown lenses, whichever colour they want to see the world in. For mirror finish though, the story is usually opposite. If you have a blue mirror finish lens, It will reflect most of the blue light and you will see a completely different colour (absence of blue) through it.

People who wear powered lenses has option to make prescription sunglasses. Prescription sunglasses can be super expensive. Many people go for clip-on sunglasses instead. I personally dislike clip-on sunglasses.

To conclude:

Sunglasses aren't just fashion accessory, they are extremely useful during sunny days. I really don't know too much about them, but I tried to share what I learned from my research. Hope it helps someone buy their own pair of sunglasses. Let me know in the comment if you want to see more of my buying guides.