4 Mil Vs 8 Mil Window Security Film: Which Should You Choose

Glass has been used for windows for thousands of years. The Romans are likely to have been the ones who first used glass for windows in Egypt around 100 AD. Before that glass, cloth, wood or paper was used to cover window openings. In this day and age paper would be utterly useless – besides not being transparent it would provide zero security for your home!  But even glass must be protected from burglars to prevent break-ins.

There are many ways to help secure your windows and window security film is one of them. Security film is produced by laminating together various layers of polyester film using special adhesives. Glass that is covered with security film is far harder to break. While the outer glass will crack (the film holds the pieces of glass together thus preventing it from shattering), the inner glass is more resilient against damage.

But as you may know, security film comes in different thicknesses. How do you choose which thickness will suit your requirements the best? How do you know which thickness provides sufficient protection for the size of the window so that you don’t spend more than you need to?

In this article we will explore two of the most common thicknesses used for residential installations – 4mil and 8 mil – and weigh in the pros and cons of both.

What’s the Difference?

The recommendation is to select the security film according to the size of your window. If you have a small window, you can apply a thinner film while a large window will require a thicker one.

In general, the thicker films are more hard-wearing with far less likelihood of being torn or punctured. Thinner films are more often used for protection against the sun.

Of course, the thicker the security film, the higher the cost. Nanotechnology has been used by manufacturers to make thinner films even stronger than thicker ones, but again, these come at a price.

4 Mil – 100 microns

4 mil Clear Window Film


  • 4 mil (100 microns) film has enough strength to appreciably reduce the risk of being cut by the glass should the window be broken.
  • Your window will comply with the human impact safety standard (AS1288) once you apply a 4 mil security film to it.
  • It will provide protection against graffiti and minor vandalism.
  • It is easy to remove and replace if needs be.
  • 4 mil window security film provides excellent protection against the sun, protecting furniture from damaging UV rays.
  • A 4 mil film is fairly easy to apply yourself.



  • Only useful in a low-threat environment.
  • They do not stop your house from getting hot.
  • Not rated for “Large Missile Impact” – i.e. will not stop catastrophic failure of the glass if a large object is thrown through the window

8 Mil – 224 microns


  • For a window with an area of 1.8m2 (2.15 ft2) or less, you can use 8 mil film which can stand up to 35kg / m2 (77lb / 10.8 ft2)of force. This is strong enough for medium-sized windows that are on the first floor of offices or residences.
  • Certified for “Large Missile Impact”. No, this does not mean that it will stop an actual missile, but it will stop a large rock or other similar objects from penetrating the window.
  • The installation of 8 mil security film will almost certainly deter criminals from breaking in as gaining entry through the broken window is much harder to do.
  • This thickness of film helps to control glare from the sun as well as control the heat in your house.
  • Some films can aid daytime privacy.
  • This film will protect your furniture against harmful UV rays.
  • An 8 mil film will provide protection against graffiti – if it is vandalized, simply peel it off and replace it. Or alternatively, you can lay down two layers and when one is damaged, simply peel off that layer and the underlying layer is ready to go.


  • For windows larger than 1.8m2 (2.15 ft2) it is recommended that 12 mil film be applied.
  • 8 mil film will probably require professional installation.
  • 8 mil security glass film is not bulletproof!


Frequently Asked Questions

Do I install security film on the interior or exterior of the glass?
It is usual to apply the security film to the exterior of the window, but it can be applied to the interior where the context allows – for example, on a hard-to-reach window like a skylight or dormer window.

Is it a noisy installation process?
If old film must be removed first it might be a little loud, but in general, the installation process is not noisy.

Is it okay to install security film on top of the existing window film?
It is not recommended. If two layers of window film are put on top of each other, the warranty could be voided.

Can I use security window film on my car window?
Yes, most security films can be installed on car windows. Check the product description first as there are exceptions.

What is the cost of security film?
Prices will vary depending on the manufacturer. Tinting and the type of film will also affect the price. Have a look at Amazon to get an idea of pricing.

Does security film come with a warranty?
Each manufacturer offers a different warranty. They are generally based on the type of film installed. Solar films used for residential purposes usually come with a lifetime limited warranty. Commercial installations usually come with a 10 to 15-year limited warranty. Exterior installations usually have a 5 to 7-year warranty.

Will my new security film bubble?
Water bubbles may be in evidence during the drying process. This is usually just residual moisture that is trapped under the film, and it will evaporate as the film dries. This can take up to 2 months. Don’t press on the bubbles as this could damage the film.

Can I remove the security window film?
Yes, you can. Security film is removable. However, it is not so easy to remove that you need to worry about intruders removing it. It is best to get a professional company to remove the film for you.

Can I get different shades of window security film?
Yes. You can choose from a clean film, a neutral film, or a reflective film that looks like a one-way mirror.  The neutral film will have a tint.

What are the uses of security window film?
Security film strengthens glass up to 2-3 times. It will keep your glass intact when someone, or something, hits it. It will prolong the time it takes for a burglar to get through the window. It prevents the glass from shattering thus increasing safety. Security films block 99% of UVA and UVB rays.

Can I clean security window film?

Yes. Clean it with a non-abrasive material like a microfiber cloth. Use ammonia-free cleaning liquids. Don’t clean your windows until the drying period is over.

How long does security film last?
It can last quite a few years depending on the surface it is applied to and the location of the windows. Interior film will last longer than that applied externally.

Is it worth it?
Security glass film does not give a 100% guarantee of protection. However, it certainly adds a layer of security that can give you a bit more peace of mind.

 Does installing window security film affect the value of my house?
While you can’t really set a particular dollar amount to it, buyers will certainly appreciate the extra security offered by window film as well as the other benefits of UV protection and temperature control.

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