# How strong of a magnet do I need? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [September 12, 2018, 8:21pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238 "2018-09-12T20:21:56Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Grrr](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/grrr/32/146_2.png) [@Grrr](https://boards.straightdope.com/u/Grrr)\ **Post date:** [September 12, 2018, 8:21pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/1 "2018-09-12T20:21:56Z")
I need a magnet that I can stick to the interior roof of my car. That shouldn’t be a problem should it? As far as I can tell, there’s only a thing piece of fabric separating the metal from the would be magnet. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [September 12, 2018, 8:34pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/2 "2018-09-12T20:34:25Z")
I wouldn’t go with anything less than neodymium. Go to KJMagnetics and see what they have. I’ve ordered from them before and always been happy. They’ll have just about every size and shape you can think of. You could probably also shoot them an email explaining what you’re trying to do and see if they have any ideas. ---
**Author:** ![Alpha\_Twit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alpha_twit/32/265_2.png) [@Alpha\_Twit](https://boards.straightdope.com/u/Alpha_Twit)\ **Post date:** [September 12, 2018, 8:34pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/3 "2018-09-12T20:34:44Z")
Depending on your car model, the cloth headliner will be glued to a fiber/cardboard backing and there will probably be some level of insulation between that and the metal. I’m not saying you can’t stick a magnet to the interior of the roof but you’re just going to have to experiment and find what works. More info would help but even then, any answer we could give is little better than guesswork. ---
**Author:** ![Grrr](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/grrr/32/146_2.png) [@Grrr](https://boards.straightdope.com/u/Grrr)\ **Post date:** [September 12, 2018, 8:41pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/4 "2018-09-12T20:41:34Z")
OK, I guess I’ll give more info, I was a little embarrassed because it sounds so silly. When I’m on break at work, I like to go out to my car and watch Netflix. I’d like to be able to lay my seat all the way back and mount my phone on the roof so I can still watch “TV”. That’s all I’m trying to do; as silly as it sounds. 🙂 ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [September 12, 2018, 8:44pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/5 "2018-09-12T20:44:51Z")
I just tried two of my neodymium magnets. Let me preface this by saying that the headliner in my car isn’t the typical fabric and insulation glued to the roof. It’s more of a ‘shell’, like something that would crack if you hit it, because of that, I don’t know that it actually gets all that close to anything metal up there. I have a cylinder that’s about a half inch in diameter and 3/4 of an inch long that didn’t do anything. I also tried a half inch cube. It could ‘feel’ the steel, but it wasn’t going to stay. Even with a ‘regular’ headliner, I think you’d need something stronger than those so it can compress the insulation and get much closer to the steel. You’d need, I think, to start looking at cubes (if that’s the shape you wanted) about 3/4 or an inch. You do have to be careful with those. Once they start getting up over a half inch or so, you can do some real damage (to yourself). ---
**Author:** ![Alpha\_Twit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alpha_twit/32/265_2.png) [@Alpha\_Twit](https://boards.straightdope.com/u/Alpha_Twit)\ **Post date:** [September 12, 2018, 8:47pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/6 "2018-09-12T20:47:09Z")
My apologies, I should have been more clear. More info about _what type of car_ you have is what I’m wondering. Different cars have different structures. Luxury cars tend to have more insulation and thus you need a stronger magnet. Why you want the magnet is your business. It’s not relevant to me. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [September 12, 2018, 8:47pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/7 "2018-09-12T20:47:45Z")
> [@Grrr](#): > > OK, I guess I’ll give more info, I was a little embarrassed because it sounds so silly. > > When I’m on break at work, I like to go out to my car and watch Netflix. > > I’d like to be able to lay my seat all the way back and mount my phone on the roof so I can still watch “TV”. > > That’s all I’m trying to do; as silly as it sounds. 🙂 Get some velcro. Stick half to the ceiling and the other half to a case that you just use for that purpose. Actually, that’s probably going to pull the velcro off the ceiling after a while. If you’re willing to make a small cut in the headliner, you could slide a magnet above the headliner and stick it right to the ceiling, then use a magnetic phone case for holding it. ---
**Author:** ![Grrr](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/grrr/32/146_2.png) [@Grrr](https://boards.straightdope.com/u/Grrr)\ **Post date:** [September 12, 2018, 8:55pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/8 "2018-09-12T20:55:05Z")
> [@Alpha\_Twit](#): > > My apologies, I should have been more clear. More info about _what type of car_ you have is what I’m wondering. Different cars have different structures. Luxury cars tend to have more insulation and thus you need a stronger magnet. > > Why you want the magnet is your business. It’s not relevant to me. Oh okay. It’s a 2013 Prius. > [@Joey\_P](#): > > Get some velcro. Stick half to the ceiling and the other half to a case that you just use for that purpose. > Actually, that’s probably going to pull the velcro off the ceiling after a while. > > If you’re willing to make a small cut in the headliner, you could slide a magnet above the headliner and stick it right to the ceiling, then use a magnetic phone case for holding it. Thanks for your input. I thought of Velcro, but decided against it because sticky things tend to become unstuck in this Texas heat. Your info about the magnets was quite helpful though. ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [September 12, 2018, 9:21pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/9 "2018-09-12T21:21:25Z")
My car has those hang-on-for-this-curve handles on both sides, does yours? (I am thinking of stringing cords between them.) ---
**Author:** ![swampspruce](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/swampspruce/32/261_2.png) [@swampspruce](https://boards.straightdope.com/u/swampspruce)\ **Post date:** [September 12, 2018, 10:33pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/10 "2018-09-12T22:33:25Z")
Any reason you couldn’t use something like Google Cardboard? I know VR in the car sounds weird but it would save you some aggro. [https://www.vrheads.com/how-watch-netflix-google-cardboard](https://www.vrheads.com/how-watch-netflix-google-cardboard) **PLease** ignore the next article… unless you don’t . ---
**Author:** ![peccavi](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peccavi/32/388_2.png) [@peccavi](https://boards.straightdope.com/u/peccavi)\ **Post date:** [September 12, 2018, 11:54pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/11 "2018-09-12T23:54:46Z")
This may be simplistic, but why hang it from the ceiling? Flip the problem. What about a long selfie stick stuck into something like a small Christmas tree stand on the floor? I don’t know enough about the layout of a Prius seat and floor to say it would definitely work, but it would certainly be cheap, and easy to set up and take down. ---
**Author:** ![Gatopescado](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gatopescado/32/5711_2.png) [@Gatopescado](https://boards.straightdope.com/u/Gatopescado)\ **Post date:** [September 13, 2018, 12:07am UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/12 "2018-09-13T00:07:47Z")
As a bit of a Magnet King, I’m wondering if one strong enough to hold it to the roof wouldn’t seriously mess up the phone/screen. Don’t know Jack about cell phone screens. I’ve got magnets that hold 2" drop receiver hitches to the sides of truck bodies. :eek: If you’re not careful, they’ll rip the skin right off your fingers. So, if all else fails, I’ve got one. 😉 ---
**Author:** ![Beckdawrek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beckdawrek/32/3647_2.png) [@Beckdawrek](https://boards.straightdope.com/u/Beckdawrek)\ **Post date:** [September 13, 2018, 12:16am UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/13 "2018-09-13T00:16:14Z")
Yep. The magnet might not be too good for the phone. I bet Sharper Image has something for just this usage. But a dollar store selfie stick should work. Your could Magyver it, surely. Like peccavi said. ---
**Author:** ![jnglmassiv](https://avatars.discourse-cdn.com/v4/letter/j/f07891/32.png) [@jnglmassiv](https://boards.straightdope.com/u/jnglmassiv)\ **Post date:** [September 13, 2018, 3:47pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/14 "2018-09-13T15:47:23Z")
If you go with a magnet, consider the base for a magnetic antenna mount. It should hold without a problem and is drilled so you could add a gooseneck. These kind of antennas are often called magmounts. ---
**Author:** ![Hopeful\_Crow](https://avatars.discourse-cdn.com/v4/letter/h/da6949/32.png) [@Hopeful\_Crow](https://boards.straightdope.com/u/Hopeful_Crow)\ **Post date:** [September 13, 2018, 6:04pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/15 "2018-09-13T18:04:59Z")
I did a Google search for flexible phone holders and found lots of intriguing options. Most seem to be gooseneck affairs with a clip or clamp on one end that would be great to attach to your rear view mirror or the handle above your door. I like the fact that you can adjust the distance of your phone from your eyes. I’d worry about a strong magnet affecting your phone, too. You could permanently ruin it with one. ---
**Author:** ![Cheesesteak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cheesesteak/32/3694_2.png) [@Cheesesteak](https://boards.straightdope.com/u/Cheesesteak)\ **Post date:** [September 13, 2018, 6:10pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/16 "2018-09-13T18:10:12Z")
> [@peccavi](#): > > This may be simplistic, but why hang it from the ceiling? Flip the problem. What about a long selfie stick stuck into something like a small Christmas tree stand on the floor? . I’m down with this idea. Stick the handle in between the seat and the console to stabilize it, and you have your answer for just a few bucks. ---
**Author:** ![Grrr](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/grrr/32/146_2.png) [@Grrr](https://boards.straightdope.com/u/Grrr)\ **Post date:** [September 13, 2018, 6:26pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/17 "2018-09-13T18:26:44Z")
> [@Hopeful\_Crow](#): > > I did a Google search for flexible phone holders and found lots of intriguing options. Most seem to be gooseneck affairs with a clip or clamp on one end that would be great to attach to your rear view mirror or the handle above your door. I like the fact that you can adjust the distance of your phone from your eyes. > > I’d worry about a strong magnet affecting your phone, too. You could permanently ruin it with one. Aw man, thanks for that. Using your search, I found a mount that fits around your neck _specifically_ designed so you can watch the phone while laying down. That’s exactly what I need. And only $20 on Amazon. ---
**Author:** ![Hopeful\_Crow](https://avatars.discourse-cdn.com/v4/letter/h/da6949/32.png) [@Hopeful\_Crow](https://boards.straightdope.com/u/Hopeful_Crow)\ **Post date:** [September 14, 2018, 6:15pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/18 "2018-09-14T18:15:27Z")
You’re welcome, **Grrr!** I actually had something else in mind that I thought could be jury-rigged into what you wanted but didn’t know what to call it so I started out by Googling “flexible.” Wouldn’t you know “phone holders” was one of the first results that came up? I wasn’t expecting that to work out so well but in retrospect, it make sense that someone had come up with a solution to that problem. Hey, I finally got to be the first to come with a solution for a Doper’s conundrum. Cool! I hope what you ordered works out for you. ---
**Author:** ![Ellecram](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ellecram/32/18948_2.png) [@Ellecram](https://boards.straightdope.com/u/Ellecram)\ **Post date:** [September 15, 2018, 10:16pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/19 "2018-09-15T22:16:47Z")
Wow. I just discovered something I didn’t even know I needed! Think I will be ordering one myself. ---
**Author:** ![Spiderman](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spiderman/32/230_2.png) [@Spiderman](https://boards.straightdope.com/u/Spiderman)\ **Post date:** [September 17, 2018, 5:23pm UTC](https://boards.straightdope.com/t/how-strong-of-a-magnet-do-i-need/821238/20 "2018-09-17T17:23:27Z")
> [@Grrr](#): > > Aw man, thanks for that. Using your search, I found a mount that fits around your neck _specifically_ designed so you can watch the phone while laying down. That’s exactly what I need. And only $20 on Amazon. I have a _strong_ neodymium magnet on a wearable light; strong as in don’t have your fingers in between the two halves if they get within 6" -1 " of each other. Yeeowwch! Strong as in I can’t separate the two halves with just one hand. I tried it in my Mazda (so not even a luxury vehicle); wouldn’t stick to the inside of the roof despite sticking to the exterior just fine. Too much padding.