How to choose hiking sunglasses and my pick27% light transmission at 20g

Choose hiking sunglasses not by how dark the lens looks, but by two numbers: visible light transmittance and UV transmittance. My pick is the SWANS Df.Pathway polarized lens model, with 27% visible light transmittance at 20g. I also picked a hat and a backup light, and the three come to 131g.

You can't choose hiking sunglasses by how dark the lens is

A jet-black lens doesn't necessarily protect better against UV. Even a dark lens doesn't always block UV, and UV protection is a separate feature.

There are two numbers to read. For glare, visible light transmittance; for UV, UV transmittance (or the UV cut rate). This article makes the sunglasses the lead and picks one each for a hat and a backup light.

How I chose

The first thing I looked at was the UV transmittance label. All three were labeled as cutting 99% or more, so there was no difference there. Next I checked visible light transmittance against the 20–40% that SWANS gives as its summer-mountain guide. Last I laid weight and price over it and calculated price per gram. This pick is made from what you can buy on Rakuten. mont-bell, sold only through its official shop, appears as out of ranking with its numbers.

• Check the UV transmittance label first (a separate number from how dark the lens is)
• Aim for 20–40% visible light transmittance (easy to keep on even in forest)
• Decide between polarized and photochromic by where you walk and the temperature

Comparing 3 pairs of hiking sunglasses by visible light transmittance and weight

On UV, the two SWANS are labeled 0.1% UV transmittance or less (UV cut of 99.9% or more), and mont-bell is labeled UV cut of 99% or more. The weights of the three differ by only 3g. The differences are visible light transmittance and price per gram.

My sunglasses pick: SWANS Df.Pathway polarized | 27% light transmission at 20g

I'll say this with some heat. 27% is almost the middle of the 20–40% that SWANS itself gives as its summer-mountain guide, and at 20g it's the lightest of the three. It's labeled with 97% or more polarization, built to cut glare off snow gullies and water.

Here's the weak spot. SWANS writes that with polarized lenses, phone and camera screens can be hard to see depending on the angle. If you walk while looking at a map app, check your own phone in the shop before buying this one.

If you choose by photochromic lens: SWANS LUNA | changes from 84% to 10%

The lens darkness changes with the amount of UV, and visible light transmittance moves from 84% to 10%. That's a range you can keep on from a dark forest before dawn up to the ridge.

What to watch is temperature. The official caution says the lens tends to get lighter in hot summer weather. It costs ¥3,850 more than my pick, at ¥917 per gram. It suits people who start walking in the dark of the morning.

My hat pick: The North Face Horizon Hat | about 85g with a chin strap

You wear it together with the sunglasses, so I chose the hat for lightness and wind. In size L it's about 85g, with a removable chin strap and size adjustment, and mesh around the head.

Here's the weak spot. The UV label is UPF15–30 (85% or more UV cut), not UPF50+. If you put the number first, compare the labels and choose a different hat. SWANS recommends trying on sunglasses together with a hat.

My backup light pick: Petzl e+LITE | 26g, and 10 years with the battery in

A backup is gear you don't use on most days. So I chose it not by brightness but by lightness and how many years it keeps. The official page says it's 26g and can be stored for 10 years with the battery in and ready to use.

Here's the weak spot. Brightness is a maximum of 40 lumens, with a burn time of 3.5 hours (9.5 hours at 20 lumens). It won't be your main light for walking through the night. For your main light, choose from headlamp rankings, ranked by weight and burn time.

Out of ranking: mont-bell sunglasses and gloves (bought at the official online shop)

The PL Trekking Glass is 23g and ¥11,000. It's 3g heavier and ¥4,400 cheaper than my pick, and its ¥478 per gram is the lowest of the three. The two in-stock colors are 15% and 18%, on the darker side of SWANS's guide.

For thin gloves, the Wic.UV Tect Trekking Gloves average 24g for the pair at ¥3,300. They're labeled UPF50+, and the official description says they're for spring and summer trekking and hiking.

Visible light transmittance and UV transmittance are measured separately

According to the Consumer Affairs Agency's explanation of the Household Goods Quality Labeling Act, sunglasses must label visible light transmittance and UV transmittance, each measured in a separate test (the visible and UV tests of JIS T 8141). The two aren't linked.

Another rule: a photochromic lens must label its visible light transmittance as "the value at its darkest." Only lenses with 90% or more polarization can call themselves polarized sunglasses.

Sunglasses, hat and light total 131g

Together, 131g. More than half is the hat. If you want to go lighter, what to cut is the hat, not the 3g of the sunglasses.

Who is each for? Split by situation

• A day hike moving between summer ridge and forest: my pick, the Df.Pathway. 27% is dark enough to keep on as you enter the forest.
• A trip that starts walking before dawn: the photochromic LUNA. While it's dark it lightens to 84%.
• Days of long walks on snow gullies or by water: the two polarized pairs. They're built to cut glare.

If you spend a long time walking while looking at a map app, the photochromic LUNA is another way to choose. I compared the emergency gear you keep at the bottom of the pack with the backup light in the emergency blanket and zelt article.

If you already own a pair that labels UV transmittance and has 20–40% visible light transmittance, what you have is enough. For glasses wearers, SWANS separately offers over-glasses and clip-on types, and for snow season there are other ways to choose (the three here are for outside snow season).

FAQ

What visible light transmittance is good for hiking sunglasses?

A rule of thumb for summer mountains is around 20–40% (SWANS's guide). The reasoning is that within this range, you can keep them on and still get bright enough vision in dim valleys and forest.

Do I need polarized lenses for hiking?

They help when you want to cut glare on a sunny high mountain or on a snow gully. While they cut glare, the lens is darker, and a phone screen may be hard to see.

Do darker lenses block UV better?

Not necessarily. Darkness is visible light transmittance, while UV is UV transmittance, a separate number. SWANS labels all its lenses as cutting 99.9% or more, regardless of color or brightness.

Gear in this article

Ad · Images: Rakuten Ichiba

SWANS Df.Pathway polarized lens model PW-0051SWANS LUNA photochromic lens model LN-0066ZThe North Face Horizon Hat (unisex)Petzl e+LITE

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