How To Tell If A Mirror Is Two Way Or Not: 8 Steps (with Pictures)

Skip to ContentQuizzes

• PRO Courses Hot Guides Tech Help Pro Expert Videos About wikiHow Pro Upgrade
• QUIZZES All Quizzes Hot Love Quizzes Personality Quizzes Trivia Quizzes Taylor Swift Quizzes
• EDIT Edit this Article
• EXPLORE Tech Help ProAbout UsRandom ArticleQuizzes Request a New ArticleCommunity DashboardTrendingForums Arts and EntertainmentArtworkBooksMoviesComputers and ElectronicsComputersPhone SkillsTechnology HacksHealthMen's HealthMental HealthWomen's HealthRelationshipsDatingLoveRelationship Issues Hobbies and CraftsCraftsDrawingGamesEducation & CommunicationCommunication SkillsPersonal DevelopmentStudyingPersonal Care and StyleFashionHair CarePersonal Hygiene Quizzes Love Quizzes Personality Quizzes Fun Games ForumsArts and EntertainmentFinance and BusinessHome and Garden Relationship QuizzesCars & Other VehiclesFood and EntertainingPersonal Care and Style Sports and FitnessComputers and ElectronicsHealthPets and Animals TravelEducation & CommunicationHobbies and CraftsPhilosophy and Religion Work WorldFamily LifeHolidays and TraditionsRelationships Youth
• LOG IN

  Log in

  Social login does not work in incognito and private browsers. Please log in with your username or email to continue. Facebook Google wikiHow Account No account yet? Create an account
• RANDOM

• Home
• Random
• Browse Articles
• TrendingNew
• Quizzes & Games
• All QuizzesHot
• Love Quizzes
• Personality Quizzes
• Fun Games
• Dating Simulator
• Learn Something New
• Forums
• Courses
• Happiness Hub
• Explore More
• Support wikiHow
• About wikiHow

• Log in / Sign up

Terms of Use wikiHow is where trusted research and expert knowledge come together. Learn why people trust wikiHow

• Categories
• Arts and Entertainment
• Artwork
• Framing
• Mirrors

How to Tell if a Mirror Is Two Way or Not Download Article The ultimate fake mirror tests to spot two-way mirrors Co-authored by Carl Clatterbuck

Last Updated: July 21, 2025 Fact Checked

Download Article

• Considering the Location
|
• Examining the Mirror
|
• Video
|
• Q&A
|
• Warnings

|Show more |Show less ARTICLE VIDEO X

This article was co-authored by Carl Clatterbuck. Carl Clatterbuck is a private investigator based in Michigan. With nearly 40 years in the industry, Carl is known for providing premier private detective services for law firms, businesses, corporations, and individuals throughout the US and around the world. The Carl H. Clatterbuck Agency has successfully completed thousands of cases, specializing in high-profile criminal defense cases helping to resolve cases involving multiple homicides, missing persons, white-collar crimes, and more. His cases have both state-wide and national significance. Carl is a nationally published writer and has worked as an editor and a reference librarian. Carl has experience teaching at both high school and college level, most recently teaching a series in the techniques of interviewing and investigation. His professional practices have also qualified him to give testimony as an expert witness in numerous jurisdictions. He has a degree in English from the University of Michigan and an MFA from the University of Montana. This article has been fact-checked, ensuring the accuracy of any cited facts and confirming the authority of its sources. This article has been viewed 3,027,833 times.

Have you ever been in a bathroom, dressing room, hotel room, or another private area with a mirror and had that feeling that someone is watching you? You can check to see if a mirror is transparent by observing how it is installed and using a few simple techniques to determine if there's a wall behind it. You may have heard about the fingernail test but there are more accurate ways to tell if a mirror is two-way or not.

Signs a Mirror is Two Way

Lack of a gap between a mirror and wall can indicate a two-way mirror. You can also try to see if there's a room on the other side of the mirror by dimming the lights and shining a phone light or flashlight through, or tapping the glass to listen for hollow sounds. If all else, fails, try to touch your finger to the glass, and if it looks like you can actually "touch" your reflection, it might be a first-surface mirror (which would be rare) or two-way mirror.

Steps

Part 1 Part 1 of 2:

Considering the Location

Download Article

1. 1 Observe how the mirror is installed. Notice if the mirror seems to be hanging on the wall or if it's part of the wall itself. If it appears to be hanging, try to look behind it and see a wall. If the mirror seems to be part of the wall itself, there's a good chance it's a two-way mirror, which must be set into the wall rather than hung onto it. That way, people standing on the other side of the wall can observe someone looking in the mirror.
   • A two-way mirror is a piece of glass coated with a substance called a micro pane. If you stand on the treated side, you see your reflection but the untreated side looks like a tinted window.
   • If you see a wall behind the mirror, it's a good bet that it's nothing more than a regular mirror.
2. 2 Check out the lighting. Look around and determine whether the lighting seems extraordinarily bright. If so, you might be looking at a two-way mirror. However, if the light in the room is relatively dim, and you can't immediately see through the mirror, it's probably just a standard mirror.[1]
   • For a two-way mirror to be effective, the light on the mirrored side needs to be 10 times brighter than the light on the other side. If the lighting is dimmer, it's possible to see through the glass to the observation area.
   Advertisement
3. 3 Consider where you are. If you're in a public place and in an area where you'd expect privacy, such as a restroom or hotel room, it's unlikely and illegal to have a two-way mirror. On the other hand, two-way mirrors are frequently used by law enforcement. For example, two-way mirrors are used in interrogation rooms and for lineups.
   • The use of two-way mirrors is closely tied to issues of personal privacy and Constitutional rights. Most states have passed additional legislation preventing the use of two-way mirrors in rest rooms, locker rooms, showers, fitting rooms, and hotel rooms.[2] For example, according to the 2006 New York Code, if a location in that state has chosen to use two-way mirrors for surveillance, they are required to post signs that notify you.[3]
   • Many places, such as gas stations, will use one-way metal mirrors because glass mirrors can be destroyed by users. If the mirror in question is metal, then it is not a two-way mirror.
   EXPERT TIP

   Carl Clatterbuck

   Private Investigator Carl Clatterbuck is a private investigator based in Michigan. With nearly 40 years in the industry, Carl is known for providing premier private detective services for law firms, businesses, corporations, and individuals throughout the US and around the world. The Carl H. Clatterbuck Agency has successfully completed thousands of cases, specializing in high-profile criminal defense cases helping to resolve cases involving multiple homicides, missing persons, white-collar crimes, and more. His cases have both state-wide and national significance. Carl is a nationally published writer and has worked as an editor and a reference librarian. Carl has experience teaching at both high school and college level, most recently teaching a series in the techniques of interviewing and investigation. His professional practices have also qualified him to give testimony as an expert witness in numerous jurisdictions. He has a degree in English from the University of Michigan and an MFA from the University of Montana. Carl Clatterbuck Private Investigator

   If you suspect a hotel room is bugged, the first step is to go to the authorities. The only people with access would be hotel staff or someone they let in. If you need proof, you can request security footage from the hotel hallways or lobby. If the hotel refuses to cooperate, a lawyer can subpoena the footage and records to investigate further.

Advertisement

Part 2 Part 2 of 2:

Examining the Mirror

Download Article

1. 1 Try to peer through the glass. Press your face up to the mirror and cup your hands around it, creating a dark tunnel to block out as much light as possible. When you do this, if the light in the observation room is at all brighter than the light on your side of the mirror, you should be able to see something beyond the glass.
2. 2 Shine a light on it. If you're still not convinced, turn off the lights, then hold a flashlight to the mirror (it can even be the "flashlight" on your smartphone). If it is a two-way mirror, the room on the other side will be illuminated and you'll be able to see it.
3. 3 Sound it out. Tap on the surface of the mirror with your knuckle. A normal mirror will produce a dull, flat sound since it's placed in front of a wall. An observation mirror will produce an open, hollow, and reverberating sound because there is an open space on the other side.[4]
   • The sound of tapping a two-way mirror has also been described as bright or sharp as opposed to a thud from an everyday mirror.
4. 4 Perform the fingernail test. While it is not completely accurate, you can use your fingernail to determine if the mirror is a first or a second surface mirror. Simply place your fingernail on the surface of the mirror. When you touch your fingernail to a second surface mirror, you can't touch your own reflection; instead, you will see a gap caused by a second layer of glass over the mirrored surface. When you touch your finger to a first surface mirror, you can touch your own reflection, since there's no additional layer of glass in between. First surface mirrors are very rare, so if you find one there's likely to be a very specific reason and it's very possible that it's a two-way mirror. Second surface mirrors are your ubiquitous everyday mirrors.[5]
   • Due to variables like lighting and the material with which the mirror is manufactured, it can be really difficult to tell whether you are truly touching your reflection or not. You might think you're touching a first surface mirror when you're actually not.
   • Also, it's possible for a two-way mirror to be a second surface mirror. If other aspects of the situation, like the mirror's setting and lighting, have indicated that what you're seeing is a two-way, don't let the fingernail test be the deciding factor.
5. 5 Consider the extreme measure of breaking the glass. If it's a regular mirror, it will shatter and you'll see the mirror's backing or a solid wall. If it's a two-way mirror, you'll see the room behind the mirror. You should probably only consider this option if you feel threatened or are in danger. Breaking the glass will cause damage and create a safety hazard.
Advertisement

Community Q&A

Search Add New Question

• Question Are department stores allowed to have two way mirrors in fitting rooms? Community Answer No, they are not! If you suspect there is a two way mirror in a fitting room, report it to the police. Thanks! We're glad this was helpful. Thank you for your feedback. If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow Yes No Not Helpful 66 Helpful 474
• Question What should I do if I suspect a two-way mirror in a dressing room of a store? Community Answer Get out of there as quickly as possible, and alert a law enforcement official of your suspicion so that they can definitively investigate and decide if it is a two-way mirror. Thanks! We're glad this was helpful. Thank you for your feedback. If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow Yes No Not Helpful 72 Helpful 540
• Question If a mirror looks like its see-through, is it a 2 way mirror? Community Answer It’s likely. Try shining a light through to see if there’s something on the other side. Thanks! We're glad this was helpful. Thank you for your feedback. If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow Yes No Not Helpful 54 Helpful 273

See more answers Ask a Question 200 characters left Include your email address to get a message when this question is answered. Submit Advertisement

Video

Read Video Transcript

Tips

Submit a Tip All tip submissions are carefully reviewed before being published Name Please provide your name and last initial Submit Thanks for submitting a tip for review!

Warnings

• Keep in mind that most people have no desire to go through the risk, trouble, and effort to spy. Exceptions include the proprietors of retail establishments—who often use surveillance technology in order to hold down employee theft as well as shoplifting—and numerous government agencies. Thanks Helpful 51 Not Helpful 11
• No test for a two-way mirror is definitive. There only needs to be a very small opening in the wall for a hidden camera with a fisheye lens and there won't be any giveaway illumination on the other side, or any hollow sound or anything to see with your cupped hands. Even if the mirror is a normal one, there are many other places to hide observation devices. Thanks Helpful 59 Not Helpful 14

Advertisement

You Might Also Like

How toDetect Cameras in a Mirror Finding Hidden Cameras Using Mobile Phones + Tips & Tricks How toDetect Hidden Cameras and Microphones How toMake a One‐Sided Mirror How to Find Hidden Cameras & Prevent Your Privacy from Being Invaded How toBuild a Hidden Camera Detector How toHear Through Walls How toSee Under a Door How toCheck if You Are Under Surveillance How toTell if Sunglasses Are Polarized How Different Mirrors Can Change How You Look How toTell if a Diamond is Real How toSpot a Spy How toEavesdrop Advertisement

References

1. ↑ https://www.iflscience.com/how-to-tell-if-your-hotel-mirror-is-actually-a-two-way-mirror-71789
2. ↑ https://books.google.com.ph/books?id=HEL0M-boMpgC&pg=PA51&lpg=PA51&dq=when+are+two+or+one+way+mirrors+legal&source=bl&ots=9jqvXs0-y6&sig=T-NDXIJWqQy_Dqok2XeX9x7JtG4&hl=en&sa=X&ei=Qz27VPunI4r5yASSxYKwAw&redir_esc=y#v=onepage&q=when%20are%20two%20or%20one%20way%20mirrors%20legal&f=false
3. ↑ https://law.justia.com/codes/new-york/2006/general-business/gbs0395-b_395-b.html
4. ↑ https://www.iflscience.com/how-to-tell-if-your-hotel-mirror-is-actually-a-two-way-mirror-71789
5. ↑ https://www.wku.edu/senate/archives/archives_2015/c-4-h-item-3c1-a-mirror-or-a-2-glass.pdf

About This Article

Co-authored by: Carl Clatterbuck Private Investigator This article was co-authored by Carl Clatterbuck. Carl Clatterbuck is a private investigator based in Michigan. With nearly 40 years in the industry, Carl is known for providing premier private detective services for law firms, businesses, corporations, and individuals throughout the US and around the world. The Carl H. Clatterbuck Agency has successfully completed thousands of cases, specializing in high-profile criminal defense cases helping to resolve cases involving multiple homicides, missing persons, white-collar crimes, and more. His cases have both state-wide and national significance. Carl is a nationally published writer and has worked as an editor and a reference librarian. Carl has experience teaching at both high school and college level, most recently teaching a series in the techniques of interviewing and investigation. His professional practices have also qualified him to give testimony as an expert witness in numerous jurisdictions. He has a degree in English from the University of Michigan and an MFA from the University of Montana. This article has been viewed 3,027,833 times. 200 votes - 86% Co-authors: 59 Updated: July 21, 2025 Views: 3,027,833 Categories: Featured Articles | Mirrors Article SummaryX

To tell if a mirror is two-way, first turn off all of the lights. Then, turn on the flashlight on your phone. Shine the light directly into the mirror. If it’s a two-way mirror, you’ll be able to see the other side. Otherwise, you'll just see your reflection. For tips on how to detect a two-way mirror by tapping on the glass, read on! Did this summary help you?YesNo

In other languages Spanish Portuguese German Italian Russian Chinese French Indonesian Arabic Dutch Hindi Korean Vietnamese Czech Japanese

• Print
• Send fan mail to authors

Thanks to all authors for creating a page that has been read 3,027,833 times.

Reader Success Stories

• 

  Angela Greene

  Sep 2, 2022

  "Cannot give an opinion right now as I have just found and read this site but I think it is brilliant! I shall..." more

More reader stories Hide reader stories Share your story

Did this article help you?

Yes No Advertisement Cookies make wikiHow better. By continuing to use our site, you agree to our cookie policy. Co-authored by: Carl Clatterbuck Private Investigator Co-authors: 59 Updated: July 21, 2025 Views: 3,027,833 86% of readers found this article helpful. 200 votes - 86% Click a star to add your vote

Angela Greene

Sep 2, 2022

"Cannot give an opinion right now as I have just found and read this site but I think it is brilliant! I shall..." more

Kay Jones

Aug 7, 2017

"Thank you so much for an informative site that has helped me discover the world of surveillance. I have found..." more

Anonymous

Aug 10, 2018

"I would say this site has helped me very much. In addition to this, I have learned how to become a Civil War..." more Rated this article:

Melinda Donohoe

Aug 26, 2016

"I liked that there is more than one way to figure out if you are dealing with a regular mirror or if it is a 2-way..." more

Gaurav Kudtarkar

Mar 8, 2016

"Very informative article. Equips you against voyeurism. After all, prevention is better than cure. Thanks wikiHow." Share yours! More success stories Hide success stories

Quizzes & Games

Can You Pass Our Lie Detector Test?Take QuizWould I Be a Good Super Spy QuizTake QuizAm I Being Gaslighted QuizTake QuizAm I Psychic QuizTake QuizDo I Need Glasses QuizTake QuizWould I Survive a Horror Movie QuizTake Quiz

You Might Also Like

How toDetect Cameras in a MirrorFinding Hidden Cameras Using Mobile Phones + Tips & TricksHow toDetect Hidden Cameras and MicrophonesHow toMake a One‐Sided Mirror

Featured Articles

115+ Brain Teasers For Adults & Kids (With Answers!)When Will I Get My First Kiss Quiz17 Believable Excuses to Miss Class At the Last MinuteHow to Speed Up Your Slow-Performing Mobile DataHow to Get a Nice BodyIce Cream Personality Test

Trending Articles

Let Us Rate You 1-10: Attractiveness Scale QuizHow Much Do I Mog QuizAm I Annoying QuizCollege Grad Intelligence Test: Can You Score An A+?How Nonchalant Am I QuizHow Weird Am I Quiz

Featured Articles

How toDress for WinterNicknames for Your Girlfriend: 125+ Funny, Sweet & Clever IdeasHow to Give Someone a Great GiftWhat Would My Life At Camp Half-Blood Be Like QuizThe Best Hairstyles for Guys with Big Foreheads22 Best Ideas for Scary (and Funny) Pranks

Featured Articles

How to Text Yourself: Fake Text Messages, Reminders, and MoreAccurate Omegaverse Quiz: 100% GuaranteeThe Hardest & Most Difficult Riddles for AdultsHow to Be More Spontaneous and Enjoy Life to the FullestHow toImprove Your PersonalitySigns You Were Meant For Greatness (Quiz)

Watch Articles

How to Marinate Chicken: 4 Recipes and a Step-By-Step GuideHow toClean Shower TileHow toDo Oblique CrunchesSimple Ways to Riffle Shuffle and Bridge Playing CardsHow toMake Black CoffeeHow toPlant a Seed in a Pot

Trending Articles

Can We Guess How Tall You Are QuizHow Would My Fandom See Me If I Were a Fictional Character QuizGet Claimed by Your Godly Parent (Percy Jackson Quiz)Am I a Furry Quiz170+ Deep, Heartfelt & Passionate Love Messages to Send Your GuyThe World's Hardest Riddles (for Kids & Adults)

Quizzes & Games

Photographic Memory TestTake QuizIs He Interested In Me QuizTake QuizAphantasia Test: How Strong Is Your Mind's Eye?Take QuizCrush Calculator: Does Your Crush Like You Back?Take QuizWhat's Your Red Flag QuizTake QuizAm I Pretty QuizTake Quiz

• Categories
• Arts and Entertainment
• Artwork
• Framing
• Mirrors

wikiHow Newsletter You're all set! Helpful how-tos delivered toyour inbox every week! Sign me up! By signing up you are agreeing to receive emails according to our privacy policy.

• Home
• About wikiHow
• Experts
• Jobs
• Contact Us
• Site Map
• Terms of Use
• Privacy Policy
• Do Not Sell or Share My Info
• Not Selling Info
• Contribute

Follow Us

×

Don’t miss out! Sign up for

wikiHow’s newsletter

Subscribe You're all set! X --567