What Sun Protection Factor (SPF) does Window Film Provide?

Think you’re safe from the sun’s harmful rays while driving or inside of a building? Au contraire! Sunlight through unfiltered glass can be just as damaging as a day at the beach. Find out how Madico® window film can provide solar protection.


Anyone who’s ever been poolside and slathered on the sunscreen can relate to the term SPF, or sun protection factor). An SPF number lets you know how effective the sunscreen will be. The higher the number, the more effective it is.

According to the American Academy of Dermatology, dermatologists recommend using sunscreen with an SPF of at least 30, to block 97 percent of the sun’s UVB rays.

So, let’s translate this to window film. This gets a little scientific, but I’ll point out the really important parts.

SPF is a measure from 280 nm (or nanometers) to 400 nm of how much ultraviolet light is transmitted.

A basic way to calculate the SPF of a product is to divide 100 by the UV transmission, for example 100/0.5 transmission = 200 SPF.

This isn’t exactly accurate as SPF goes up to 400 nm, but it provides an estimate. Every Madico film has a different SPF reading since each film is slightly different up to 400 nm.

For example, a clear film such as Clear 800 would have an SPF of 236 while a film with a lower VLT like Starlite 8 would be 2,723. A film such as UV Gard, which is designed for UV protection, has a SPF of 1937 since it blocks further into the visible spectrum than a CL 800 type of film.

Those are some pretty huge numbers compared to that 30 SPF you put on yourself.

SPF numbers are officially determined according to established testing protocols. No claims can be made about actual SPF numbers without having these tests performed by a qualified laboratory.

Suffice it to say, if you’re indoors in a building protected with window films like these, you’ll have it made in the shade with Madico.