Multiply factory glass VLT by film VLT and divide by 100. If factory glass is 70% VLT and you add 35% tint film: 70 × 35 / 100 = 24.5% resulting VLT. The result is always darker than either the glass or film alone.
- Factory windshield glass: typically 70–75% VLT (some light absorption built in)
- Factory side windows: usually 70–80% VLT (may vary by manufacturer)
- Factory privacy glass (rear): often 15–25% VLT on SUVs and trucks
- Adding 35% film to 70% factory glass: 70 × 0.35 = 24.5% resulting VLT
- Adding 5% film to 70% factory glass: 70 × 0.05 = 3.5% resulting VLT (nearly blacked out)
| Factory VLT | 50% Film | 35% Film | 20% Film | 5% Film |
|---|---|---|---|---|
| 80% glass | 40% | 28% | 16% | 4% |
| 70% glass | 35% | 24.5% | 14% | 3.5% |
| 25% privacy | 12.5% | 8.75% | 5% | 1.25% |