VLT stands for visible light transmission and is the amount of light that passes through the lens. VLT goggles that have a lower percentage are tinted darker. Darker tints are better for sunny days and bright light conditions. Low light snow goggles should have a higher VLT percentage, which allows more light to pass through and increase your visibility on cloudy or snowy days.
However, it is important to remember that not all ski goggles for low light conditions are suitable for flat-light conditions. Brands should indicate whether their VLT goggles are better for low or flat lighting conditions. A general guide to VLT percentage is:
0 - 20% for clear and sunny days
20 - 43% for partially cloudy days
43 - 80% for overcast or cloudy days
80 - 100% for night skiing conditions