How do you tell if sunglasses are polarized?

Answer 1

If they're on a rack with others, take two pair and hold them the same like you're looking through both, and then look through both lenses at once. Then rotate one pair of glasses through 90 degrees. You should have gone from seeing through both darkened lenses to not being able to see anything at all through them.

Assuming they're all by themselves - found in the bottom drawer, or on a park bench - hold them up and look at the blue sky through them. Rotate the lenses. The sky should brighten and darken through polarized lenses. Bees use the polarization of sunlight to help them navigate.

Alternately look at a digital display on a watch or other equipment through the lens (Not LED display). Rotate the lens the display will go black at part of the rotation (The display has a sheet of polarized material - reducing this solution to the first answer)

Answer 2

You can check if sunglasses are polarized by looking through them at a reflective surface like water or glass. If the lenses are polarized, you won't see as much glare, and the light should appear dimmer. You can also confirm if sunglasses are polarized by looking for a "P" or "Polarized" sticker on the glasses or checking the product description if purchasing online.