Visible Light Transmittance, commonly known as VLT, is a critical metric when selecting or installing tinted glass for vehicles or buildings. It measures the percentage of visible light that passes through the glass. A lower VLT means darker tint, while a higher VLT allows more natural light to enter.

For automotive applications, different VLT levels serve distinct purposes. A 5% VLT, often called "limo tint," blocks up to 95% of visible light, but may severely impair night driving visibility. Many jurisdictions legally require a minimum VLT of 35% for front side windows to ensure driver safety. In contrast, rear passenger windows and rear windshields often have fewer restrictions, allowing as low as 5% VLT.

For architectural use, tinted glass with VLT ranging from 20% to 65% is common. High VLT glass (50-70%) is preferred for offices and homes seeking natural brightness while still reducing heat and UV rays. Lower VLT options (15-35%) provide superior glare reduction and enhanced privacy.

It is important to note that VLT percentage is not the same as heat rejection. Some films with high VLT can still block significant infrared radiation. When choosing tinted glass, always balance three factors: visual clarity, heat control, and legal compliance. Upholding the correct VLT percentage ensures safe driving conditions and energy-efficient buildings. Always consult local regulations before installation to avoid penalties or safety hazards.