Mirrored vs polarized sunglasses: one is a coating, the other is a filter

Mirrored and polarized sunglasses are not two versions of the same thing. A mirror is a thin reflective coating on the outside of the lens: it bounces a slice of incoming light away before it enters, which makes the lens effectively darker and hides your eyes. Polarization is a film inside the lens that absorbs light vibrating horizontally, which is what reflected glare is made of; it removes the glare and leaves the scene. A lens can be mirrored, polarized, both or neither. If you want glare gone, you want polarized. If you also want a darker lens and a certain look, add a mirror. A mirror on its own does nothing for glare.

What a mirror does

A mirror coating is a very thin metallic or dielectric layer on the front surface of the lens. Part of the light hitting it reflects straight back off. The rest passes through into the lens and the tint underneath.

Three consequences:

1. The lens gets darker. Light that reflects does not reach your eye. A mirror over a given tint lets through less light than the tint alone, which is why open-water and snow lenses are so often mirrored: they get the darkness without a heavier base tint.
2. Your eyes are hidden. The outside sees the reflection, not you.
3. The colour you see on the lens is the reflection, not the view. A blue mirror looks blue to someone facing you. The wearer sees whatever base tint is under it, usually grey or brown. Most makers do not state the base tint, and the one we buy from does not; our lens colour guide is plain about that.

What a mirror does not do is anything selective. It reflects all orientations of light equally. Glare goes through it at the same rate as everything else.

What polarization does

Light reflected off a flat surface at a shallow angle comes away vibrating mostly in one plane, horizontally. That is glare. A polarizing film is a sheet of aligned molecules that absorbs light vibrating along its axis; set with that axis horizontal, it removes most of the glare and passes the rest of the scene, which is vibrating in every direction.

A polarizing film does not reflect. It does not hide your eyes. It makes the lens only slightly darker. It does exactly one thing, and it is the thing a mirror cannot do. Our polarized vs non-polarized post covers when that matters and when it gets in the way.

Side by side

Which to choose

You want glare gone. Polarized. This is the whole reason to buy polarized, and a mirror does not substitute.

You want a darker lens for water or snow. A mirror over a polarized base. The mirror handles the brightness, the film handles the glare. That is the Dark Blue Mirror and Ice Blue Mirror.

You want the look. A mirror, on whatever base suits your light. The Red Mirror sits on a warm base for patchy light.

You read a lot of screens or ski in flat light. Non-polarized, mirrored or not. The film is the thing that interferes there.

Every pair on this site is polarized; three of the five are also mirrored.

Caring for a mirror

The mirror is the outermost layer, so it is the first thing a dry wipe or a harsh chemical takes off. Rinse before wiping, use a microfibre cloth, avoid ammonia and alcohol. Our cleaning post is the method, and it matters more for mirrored lenses than any others.

Frequently asked questions