Every time I open the newspaper there seems to an article reporting that a hidden spy camera has been found in a public space.

These locations range from bathrooms to most recently Airbnb rentals.

This along with the diminishing scale of spy cameras has a lot of people wondering….

How to Detect a Hidden Camera in a Mirror?

Mirrors are a particular focus because spy cameras can easily be hidden in a two-way mirror.

If you have the time, my first advice would be to download a free app and sweep the room.

All the information on how to do that is in this article – Detect Hidden Cameras

However, if you have already done this or you don’t have the time or ability to get the app then move on to the simple steps below.

What is a two-way mirror?

It essentially works like a tinted window. However rather than a tint on the outside, it has a mirror finish. this means like a tinted widow the person on one side can see out where the person standing in front of the window/mirror is unaware.

In the movies, there always tends to be a person watching however in actuality most times it is simply a camera.

How do I test if it is a two-way mirror?

Step 1 – The installation

Take a look at the mirror, could there feasibly be anything behind the mirror?

If the mirror is on a flat wall and you are able to walk around to the other side of the wall then you can be reasonably sure that it’s not a two-way mirror.

In the instance below, the other side of the mirror is an outside wall so I can be sure that this is just a mirror.

The wall the other side is an outside wall

The wall the other side is an outside wall.

Step 2 – Location

It seems obvious but think about what somebody has to gain.

A perfect example is a changing room mirror in a public department store. It doesn’t take much imagination to understand the motivation for doing this.

On the flip side, a mirror next to a water fountain in an office corridor might be more difficult to comprehend. Why would anybody want to view people drinking water?

Step 3 – Lighting

Lighting is a big giveaway due to the fact that there must be a lot of light for the two-way mirror to work.

As stated earlier, two-way mirrors are very similar to tinted windows.

If the light in the room is very dim then the person/camera on the other side will not have enough light to view or capture what is going on.

The resolve……is to turn up the lights.

So if the lights are very bright then this might be an indication.

Also, the light will pass through the two-way mirror so the first test can be to approach the mirror and cup your hands between your eyes and the mirror.

If the observation room has a light or even if the camera has a flashing light you might be able to see it.

Use cupped hands to see if anything can be seen

Use cupped hands to see if anything can be seen

The last trick is to use a torch or even the light of your smartphone.

Hold this up to the mirror. Again if there is anything behind the mirror this will now be visible.

Step 4 – Sound

I have left this one to near the end as this is a little vague by my own admission.

Tap the mirror to see if anything seems untoward.

If the sound is not dull but appears to suggest an echo there might be something behind the mirror.

Unfortunately, this can also suggest a poorly fit mirror.

Try Tapping the Mirror to test if there is an echo

Try Tapping the Mirror to test if there is an echo

Step 5 – Finger Nail Test

While the sound test is vague the fingernail test is steeped in folklore.

It has been repeated many times as the way to detect a two-way mirror but many people dispute this.

Regardless, for completeness, it is included in this guide.

The theory is that unlike a regular mirror where you can touch your own reflection in a two-way mirror there will be a gap.

The explanation behind this is the mirror coating creates an additional layer and so there will a gap.

The Fingernail Test

The Fingernail Test

The Flipside – setting up a two-way mirror

Maybe when thinking of a two-way mirror your thoughts might flip to the idea of setting one up yourself.

Many of the tips above in detection also double up as advice to avoid detection.

Make sure the room is well lit as the light needs to pass through the mirror.

Ensure that if you do use a camera, make sure that it doesn’t have any flashing lights or anything that can be seen when using the cupping action.

Fit the mirror as firmly as possible, otherwise, the sound test might give away the location.

Lastly as detailed in this article {link} make sure this is installed in a location which is not breaking the law.


The best way to find a hidden camera full stop is to use the app detailed in this article – Detect Hidden Cameras

Foregoing that, the five steps above will give you some indication of if a two-way mirror exists.

It’s worth pointing out that although their discovery are highly publicized it still remains a very rare occurrence.

My final advice would be if you do suspect a camera, adjust your actions accordingly to make sure you don’t incriminate yourself (or expose yourself). The best advice is just to walk away if you can.

If you intend to install a two-way mirror try and make the camera as small and quiet as possible and be mindful of the law.

As always, if you are unsure of what Spy Camera to use, view ourĀ Best of Breed Spy Cameras

Happy Spying