# What's the right pull force for a magnetic door catch?

I want to install magnetic catches on a pair of closet doors. They are 90"x24" each, solid wood. They close easily but nothing is holding them closed and the clothing inside the closet tends to push them open.

According to the hardware manufacturer, there is "always one for me" but I'm not sure how to choose. Too little, and a poorly hung jacket will push it open. Too much and stresses of pulling the door open to break the catch will be so strong they will gradually damage the door one day at a time.

Anyone with experience with these?

I'm thinking 15 because I'm imagining the effort it takes to lift a 25lb dumbell, applied to my closet door many times every day. Sounds like a lot. But I don't know if that's how these catches work. The 15lb one looks like a toy.

• Why do you envision a strong magnetic force is going to "gradually damage the door? Commented Oct 14, 2021 at 15:12
• @Programmer66 the catch is at the top, the handle in the middle, 4 feet away. If the catch is too strong, every time you pull the door open it will produce stresses on the door that might eventually pry open the tenon joints and crack the paint where the panels meet the framing. I've clarified the question slightly (but not quite this much). Thank you. Commented Oct 14, 2021 at 15:16
• It's really hard to imagine that a "90 lb magnetic catch" would require 90 pounds of force to open. Most people cannot lift 90 pounds so would not be able to open a door that needed that much effort. Why would you make a catch like that? Commented Oct 14, 2021 at 15:18
• If you need more than 15 pounds to keep a closet door close, you have other problems. Commented Oct 14, 2021 at 15:18
• Look at the bright side: with the 25lb one, you could cancel your gym membership. :-)
– JACK
Commented Oct 14, 2021 at 17:59

I bought 20 pound catches. When not mounted on a door, and the catch plate mated perfectly to the magnet, perfectly aligned and flat in all six degrees of freedom, and the plate is pulled perfectly away from the magnet, in a direction perpendicular to its face with equal force from both ends, I estimate the force required to be about 20 pounds.

When mounted on a door, with the magnet on the top stop and the plate on the inner door face .... it's a different story. The door and the stop are not perfectly perpendicular in either of the two axes where they need to be. The plate does not mate perfectly with the magnet no matter how carefully you adjust it.

The mounting screws interfere slightly with the mating of the two surfaces.

Opening the door does not pull the plate in a perfectly straight line perpendicularly away from the magnet. The door twists a little and the plate comes away from the magnet with unequal forces all around its surface.

All this is very subtle and slight, but the effect is to reduce the opening force from around 20 pounds to around 2 pounds.

2 pounds is perfect for a well aligned door with no warp, no swelling or problems in the hinges, and a closet that is not overstuffed with clothes that are pushing the door open.

For all normal closets however, that have at least one or two of these problems, I would say a 40 pound magnet might be a better bet and if you want to provide any resistance that a user would think of as "strong" it would need to be a 90 pound rated one that would require a very strong pull from an average person.

• Or just install them correctly? Very tiny magnet catch can be very strong if installed properly. Commented Oct 19, 2021 at 3:40
• @nelson, if "correctly" means completely replacing your closet door with a highly engineered one made of steel, then yes. You can achieve incredibly strong attachment. There are magnetic security locks made this way that are stronger than the steel doors they lock. But for a typical residential closet door made of wood ... it's not about installation. When you use the knob to pull on the door, the door flexes a little, and the effect is to slightly pry the magnet apart rather than pull it straight apart. You could probably devise a way to reduce this problem with extra hardware. Commented Oct 19, 2021 at 13:54

These high pull-force rated catches are for use in boats or RVs where the door is going to be subject to extreme forces while staying closed. If you have a floor to ceiling door on a closet or mechanical access area, you need to make sure it stays closed even on rough water. Sure it will be hard to open, but thats the price you pay. A 90lb catch does seem extreme and would need a very specific use.

For doors in a house, you don't need much force at all to keep a door closed. The main thing pushing on a closet door is air pressure. If there is a vent in the closet and there is no catch, it could push the doors open. Also if you have double doors, the force of closing one door could make the other one pop open. I would expect something in the 15lb range or smaller would be more than enough.

I looked at some listings for typical cabinet door latches (the plastic ones with the little magnet in them)) and they don't even list pull force. I'd be surprised if they could even hold 10 lbs of force. I think the listing you pulled your image from is for unusually strong catches.

• Good points. You may be right, but in the case of my listing I think it's just misleading. The 90lb magnet is stronger than the 15lb one but the forces required to open a door held closed by them is much much less than those ratings. I ordered a 20 pound one, and I'll try to hang a 20 pound weight from it before I put it on a door. Will update. Commented Oct 14, 2021 at 21:09
• My other thought is that they rate them based on the weight of the door, but some of the item descriptions I saw really make it sound like its actually pull force. I'll be interested to know if they really hold 20lbs! Commented Oct 14, 2021 at 21:11

The Code requires a force no greater than 5 lbs. when applied to the strike side of an ADA door. (See ICC 108.1.2)