measuring penis diameter
My flaccid penis is 1.1 inches in diameter. When erect, the diameter grows to 1.24 inches. For $10 you can get a digital micrometer like this one.

(Updated April 2019) The most important step in beginning enforced male chastity is selection of your chastity device. There are many choices in construction and style. While aesthetics are important, whats more important is the fit. There are three important measurements needed to find or have built, the device right for you: flaccid penis length, diameter, and cock ring size. Chances are very good that you will not get these right the first time. To help you avoid expensive mistakes, we will guide you through the process.

We are going to discuss getting a good fit for a chastity cage. These chastity devices can be made from metal bars, solid tubes of metal, silicone, or hard plastic. They all have the same basic components: the cock or A ring, the cage or tube, and the locking mechanism. Many use small padlocks, others have built-in locks, and others use security screws. These are machine screws with encoded heads. Only a specially made screwdriver will fit the head. Each security screw has a unique design.

evolution of jail bird modifications
Here is the evolution of my Jail Bird male chastity device. Each time I had a shortened became more and more comfortable to wear.

When I ordered my first cage,I thought I did a good job. We measured and remeasured my flaccid penis at different times. Most came out to two inches. However, it turns out I was putting some pressure on the ruler and the end against my scrotum was pushing the soft flesh in so that the measurement was longer than it should have been. Finally, I thought I measured correctly. The result was a cage that was too long some of the time. Mrs. Lion measured that gap and it came out about 1/2 inch. The original cage was ordered to be 1 3/4-inches long (the measurement minus 1/4-inch per instructions). The shortened cage is 1 1/4 long. It may be slightly too short, but that is actually ok. In fact, I’m now in a cage that is just one inch long.

The A (cock) ring
The first and most difficult measurement is the diameter of the base ring. It is nothing more than a standard cock ring. This link shows a selection of standard cock rings. They are inexpensive and you will need some to determine what A ring size you will need. A cock ring is worn around both scrotum and penis. First thread each ball through and pull the skin through as well, then push the soft penis through the ring. It helps to use some hand lotion or other lube to make it easier to get your penis through. The idea is to find the smallest ring that you can comfortably wear.

Start with a one and three-quarter inch ring. Once on, can you stick a finger between the ring and your penis? If it is a tight fit, that may be the right size. Its a good start. Now, wear the ring for a minimum of three days. If you have to remove it because it is too tight, then try a size 1/4-inch larger. If it feels loose to you, try one 1/4 smaller.  Take your time. A ring fit is the most problematic. You may be anxious to start being chastised, but it wont last long if you dont have the right A ring. After two or three tries you will find the best size. Once you do, wear it for a while. See how it feels in cold environments, in the shower, as you sleep. If you do this trial for a week and you can keep it on 24/7 without discomfort, you have the right size.

Like what you are reading? Take a look at our blog. Its a daily account written by my keyholder and I of our life with enforced male chastity.

The Ever-Stretching A-Ring
One of the mysteries of the universe is that over time the A-ring seems to get larger. Now I know stainless steel is not stretching as I wear it around my cock and balls, but after a few months of continuous wear (figure around 6-8 months), the ring feels loose. In fact, the ring I started using (1 3/4 diameter) could barely accommodate one finger to the first knuckle when I started. Now, a year later, I can get my thumb between the ring and my soft penis.

Some guys will take this as a signal to order a ring that is too small, figuring they will shrink into it. Dont do it! All you will end up doing is making the device painful to wear. Just get the right size for now. If you need a smaller one later,then order it at that point. The key is to have a device that fits comfortably. Anything less will end up hurting you.

measuring penis
This is the correct measurement of my penis from the scrotum to tip. Once I realized that I was pressing the ruler into my scrotum and making me appear longer. I remeasured being careful to avoid pressing in. It made a big difference in the cage size I ordered

Penis Length
Size counts a lot in measuring for a cage. The thing is that this is not a size contest. To get the right fit, you need to know the length of your penis when completely soft. This isnt a contest. As shown in the photo, you measure under the penis with the end of the ruler just touching where your scrotum meets your penis. As you can see, flaccid size varies considerably between men. Both can achieve fully satisfying erections. The one on the left is 6 1/2-inches when hard. The one on the right is about 7-inches-long erect. This is not an easy measurement to take. Most of us get a bit excited when we are measured. Also, penis length will vary at different times. Do not measure when the penis is in the turtle mode. Take the shortest measurement for length. See image, above right for my measuring.

Most of us (males) dont realize how our flaccid penis size changes. I certainly didnt. I also didnt realize how important this measurement is when ordering a chastity device. Ive read endless forum posts and blogs about how to measure for a cage. Most are just wrong. In fact, according to a leading maker of custom chastity devices, most men order cages longer than they should. So here are some penis facts that may help you avoid this problem:

  • What most men consider their soft (flaccid) penis is very often the beginning of an erection. The reason for this is that the very act of measuring or even studying your penis tends to be exciting. Even the least, little bit of arousal will cause you to order a cage that is too long.
  • The penis is incredibly flexible when soft. A good part of the time it shrinks down a lot. When out for inspection and measurement, even if soft, it is probably 1/2-inch longer than at its true length. This is why many device makers ask you to order a cage shorter than your measurement. Mature Metal says to order 1/4-inch shorter than your measured length. I suggest making that 1/2-inch less.
  • Some keyholders say they like to see the penis grow in the cage. This will happen if the cage is too short. According to Mature Metal, the cage should always touch your penis: shaft and head. There should be no growing room.

Most cage manufacturers will either make the length to your specification or will tell you the length of the cage. How they measure the cage can matter. If they measure the bottom of the cage, then the match with your size will be perfect. If they measure in the middle it could be off a bit. It really isnt important. You actually want a cage shorter than  your soft length. You want the tip of your penis to press against the end of the cage. Good contact with the cage assures that when you pee you will minimize your chances of spraying or making a smelly mess inside your cage. Its a good idea to look for or specify a cage length 1/2-inch shorter than your smallest measurement. This allows for normal size changes.

Why is shorter better?
Mature Metal suggests that you measure the flaccid penis at its shortest, then subtract 1/4-inch for cage length. Based on my experience, most of us get cages that are too long. If the cage is longer than your true length at its shortest, the urethra will wander — it will move from the center of the cage, where there is an opening for peeing and end up so that you will spray and will have to sit to urinate. Thats what happened to me. When I had my cage shortened, my urethra actually sticks out a bit from the square opening in the Jail Bird. This assures that I can stand to pee without risk of wetting myself and the space around me.

It took me a long time to realize that the flaccid penis has a very large range of sizes. More importantly, virtually every single guy can wear a cage that’s only 1 inch long. I know that sounds odd, but it’s true. Our penises are designed to impress easily into very small spaces and they are soft. I’ve been wearing a 1 inch cage for some time now. Other guys have tried them and have similar reactions to mine: they’re perfect. Instead of taking the time and energy to try to estimate some other length, just try simple, 1 inch cage.

Another advantage of a shorter cage is that it shows much less under clothing. Its true, that to pee I have to take my balls out too since the cage holds my penis very tight to the scrotum, but with very little practice, standing at a urinal is no problem. Its interesting that even the most experienced caged males miss the importance of proper length. Your cage is too long if the head of your penis isn’t pressed firmly against the end at all times. Its not uncomfortable at all. It also gives less expansion room for those times you try to get a chubby.

As it turns out, penis diameter is probably the most important dimension for a cage. Fortunately, there isn’t too much variation between guys. As you can see in the image (left), mine is 1.1 inches. When hard, I go up to 1.16 inches; not a very big change.

It’s very important that the cage isn’t too narrow. My Jail Bird is 1.25 inches in diameter. It’s a perfect fit. Remember, the soft penis is very flexible. It’s compressed in my short, one-inch cage. Some of that compression make sure that I’m touching the sides at all times.

An inexpensive caliper, like the one in the image, is perfect for getting accurate readings. Alternatively you can lay your penis on a and get a good idea how wide it is. No matter how you measure it, be sure that the width of the cage is at least the same as your flaccid penis.

Do you really need to measure the length?
Ok, we discussed all the fine points of measuring your cock. We guys enjoy that exercise. Now let’s consider if there is a need to measure for cage ordering. The simple answer is that you do need a cage that will be about 1/4-inch narrower than your flaccid cock. You can almost certainly be comfortable in a cage less than 2 inches long. 1-1/2 inches is probably enough for almost anyone.  The only time I’ve seen issues with cage length is when they are too long. If you order a custom cage, it isn’t too expensive to adjust length if needed. But I’m convinced a cage of 1-1/2 or 1-1/4 inches long will work for almost anyone. Try for yourself. Push the head of your soft penis toward your body. It easily retracts.

There are very few off-the-shelf cages that are 1-1/2 inches or less. I found some on The quality is usually not great, but the prices are truly cheap. I suggest you buy a short cage and try it. It has to be close to the diameter of your penis. The base ring has to be right. I wrote a lot about that earlier. Give it a try. You’ll be surprised how compact your device can be.

You may not get it right the first time
Fitting a cage is not an exact science. Even with correct measurements the design of individual cages can affect comfort and fit. Most men who are caged full time have had to purchase several devices and get adjustments to ones they own before they hit the right fit. If your penis is going to be caged twenty four hours a day, the cage has to permit it to function normally and allow you to go about your life without undue discomfort. You will be in your cage a long time. Dont expect the process of finding exactly the right one to happen immediately. You may be lucky and your first cage will be your last. However, most of us have to do some trial and error before we finally get the new home for her toy right.

My Jail Bird felt great when I received it and I thought I had fit nailed. I didnt. After five months wearing it, I grew tired of the fact that my urethra was never correctly aligned with the center opening in the cage. I contacted Mature Metal, who makes the Jail Bird, and was advised that my cage was too long. As you can see that in the image (left), the penis head touches the bars at all points. This is a correct fit. If you look at my original Jail Bird (below, right),  you can see that my head isnt filling the cage. This is due to an incorrect length measurement. Apparently when I measured (top image), I pressed the end of the ruler into my scrotum. This added 1/2 inch to my flaccid length. I ordered a 1 3/4 inch cage. I should have ordered 1 1/2 inch. The cage is being adjusted and I am assured it will fit correctly when I get it back.

Choosing the device
Now that you have measurements, you are ready to go shopping. Many people, including me, start with an inexpensive imported cage. These cages will not be great fits, but will at least give you a chance to try enforced chastity without a major investment. On the other hand, buying a custom fit cage will assure the best possible experience and the two best known cage makers will adjust sizes for a nominal charge.

Plastic, silicone, or metal
Hard plastic, usually acrylic and soft silicone devices are not available in custom sizes. Most come with a variety of A rings so you can choose the one that fits best. However the cages are fixed size. Most manufacturers offer several models designed to fit different sized penises. If you can find a size that is just a bit shorter than your flaccid measurement, you will be in luck. Never order one that is longer. Shorter is always better in terms of fit. Diameter is much less of an issue. You dont want him swimming in there, but if not a tight fit, it will still work. The principle advantage of plastic and silicone is that these materials will not trip airport metal detectors. If you lock the device on with a plastic, numbered seal, you will breeze through security. However, there are some disadvantages to both plastic and silicone. Both materials tend to grip skin, silicone more than acrylic. That means the A ring will not be able to move with your body. This frequently causes friction irritation around the area it covers.  Similarly, if the plastic cage is a tight fit, it can also cause irritation.

We prefer the stainless steel cages. They come in many styles ranging from a sealed (on the end) tube with just a small hole for peeing, to an open cage like the Jail Bird shown in the image on the right. The Jail Bird is custom made by Mature Metal. This cage maker is a bit slow on delivery; it can take 8 weeks to get your custom cage, but is excellent at customer service. They will adjust the cage sizes for a $10 service charge. Steelworx in Germany is the other major cage maker. They have a similar policy about adjustments.

The Jail Bird is one of the most popular models. While its open design does permit naughty fingers some access, the tight fit prevents giving the naughty boy much benefit from his efforts. On the plus side, this design is easy to keep clean and allows the keyholder a nice view. The sharp curve of the cage both discourages erections and helps make this model invisible under clothing even for large penises like caged monkeys. Like many devices, this one requires exactly the right size A ring for maximum comfort.

Common Mistakes

maasureing erect penis
The biggest mistake people make is to buy a cage long enough to contain an erect penis. My cage is 1 1/4-inches long and my erection, as you can see, is 6-inches long.

Cage too long
The most common mistake males make when ordering a custom device is to order the cage too long. Mature Metals instructions try to convey how important it is to get this right. If the cage is too long, the head of the penis will not be in firm contact with the front bars at all times. This will result in the urethra wandering up and to one side. This makes peeing extremely chancy and makes urinating standing up very difficult. It also allows a bit too much growth space for an attempt at an erection.

Measure your flaccid penis carefully. Dont press the end of the ruler against your scrotum (MM wants you to measure from the scrotum to the tip a good idea for any custom cage). I made the mistake of doing that and my cage was 1/2 inch too long. Take this measurement several times over a few days. Chances are very good you will overestimate the length.  To avoid needing the cage adjusted, subtract 1/2 inch from your measurement for the cage length to order. When you get the device, the penis head should press firmly against the end of the cage at all times.

Base ring too small
For some reason many males believe that a smaller base ring will give them more security. The reality is that if the base ring is too tight, the device will be uncomfortable. Some males keep the area lubricated to relieve the pain. The base ring should never hurt, period. The only way to determine the correct size is to test. If you are getting a metal device, get hardware store rings (they sell them in various sizes at a very cheap price). Start with a 2-inch ring. Wear it for a few days. Chances are it is too big. If a ball escapes, it is certainly too large. If you can get more than one finger, up to the first joint between the ring and the top of your penis, it is probably too large. If you cant get a finger in, it is too small.

Dont keep trying to wear smaller and smaller rings. It isnt going to make your device more secure and it will end up making it uncomfortable. If you get a base ring that keeps your balls in front of it and is comfortable to wear, you have it right. I know a lot of people write that after they wear the device a while, they can go to a smaller ring. Why? If it does the job, leave it alone.

Listen to this post.


  1. Thank you for this post. We’re a cuckold couple and cucky is in chastity. We’re using a Curve and it’s been wonderful to read this kind of advice. It’s nice the way you did it.

  2. Hi
    my wife locked me in my acrylic chastity device again last night after a lock time out. It has been troublesome at nights when things swell. I like the feel during the day but it is bigger than the cages you recommend. Is the cage really ok at nights with spontaneous elections?

    1. Chances are that the tube is too big. What hurt me in one was the friction between my skin and the tube and base ring. If the tube “hugs” you all the way to the tip, you really can’t grow and it may not hurt you. I favor the cage type device. It lets the skin breathe and when custom made, like the Jail Bird, can fit perfectly. Mine does now and it feels good all the time. If I try to get a nocturnal erection, I don’t even feel it.

  3. Lion….. Thanks for this info its invaluable. Another measurement I’m having difficulty with is the gap between cage and ring. How do I get an accurate measurement for this one?


    1. I went with Mature Metal’s suggestion. For most of us, 3/8″ seems a good start. You probably need to start at whatever the device maker does as standard and then if you need adjustment, it is usually very cheap and easy.

  4. Enjoy the site. in total agreement with the tips on getting a good fit.

  5. When measuring for my jailbird, I found it to be very useful to use the plastic sizing kit that MM sells. It is a series of plastic rings that vary by 1″ increments and it was very useful for determining optimal cage diameter and optimal base ring diameter. I actually wore the size rings that I felt seemed optimal for 10 days continuously prior to ordering my jailbird. For length measurement, I measured the gap between the tip of my penis and the tip of the CB6000 I wore before ordering a Jailbird. I then subtracted that gap length from the length of the CB6000 cage (2 & 3/8″ if I remember correctly) to determine my flaccid length. This worked quite well for me. I’ve been kept in chastity 24/7 for 17 months with a once a month release for shaving and cleaning. My device fits well, is comfortable, prevents erections, and I have never had problems sleeping. The first time I wore it, it was on for 17 days 24/7 without any issues. My Mistress has possession of the key and she unlocks me before monthly playing (she fists me) and then she locks me back up until we play again.

    1. Dear friend:

      Please understand that fisting can be very very dangerous! Please find a new game! Take care with each other!

      Your friend,

      1. Fisting isn’t inherently dangerous. if done carefully, it can be very nice. Of course, this isn’t something you just “do”. You need to learn how and to go very very slowly.

  6. Oops! The increments are 1/8th inch increments in the sizing rings…. LOL!

  7. Hi
    I am just starting to get into chastity. I have a CB 6000s and just got sizing rings for a mature metal device. My question is how do I wear the base ring? I have one on right now and find I can slide it back a little so it sits further back, or wear it just behind my balls. To get the right size, where should it sit? I am sure there’s a sweet spot for comfort somewhere but I haven’t found it yet and I think the position of the base ring will affect the gap measurement?



    1. I keep mine as close to my body as I can.

    2. In my experience (Jailbird) the base ring that is always comfortable may be larger than that required to always keep the cage close to the groin. The area enclosed by the ring changes with activity and temperature. It is also a good reason to follow Lion’s advice to use as short a cage as possible to limit the cage weight which is mainly supported by the base ring.

  8. My hubby is a locked up cuck and he has been in chastity for 5 months now. We started out with the bird cage but that caused far too much discomfort at night. We then moved to the Holy Trainer about 2 months ago and it has perfect. Night time erections don’t hurt him, but there is enough ‘air flow’ to allow his prostate milking. The ‘trainer also is smooth all over so his panties and pantyhose don’t get damaged as much as before.

    The side note is that I wish I had put him in a cage years ago. I wish I could yell from a soap box to all the girls our there about how much you might be missing out on by not locking up your BF or hubby!!

  9. Hey there. Here’s a question for you all, regarding the A-ring width. I have the plastic test rings that mature metal sells, and after wearing them find I can’t identify the perfect size. The 1 1/2″ is the right tightness when I’m flaccid, but is painful with an erection. The 1 5/8″ is comfortable all the time, but a testicle can get loose after a while. Will the cage prevent a full erection, so that the 1 1/2″ ring won’t constrict? Or should I go with the slightly larger one and use a 1/4″ gap to prevent a ball escaping? Any help would be appreciated because I really want to get this right!

    1. The 1 1/2″ ring might be right. Mature Metal makes an oval ring that may be more comfortable. MM will adjust size if not comfortable. You can email them for advice.

  10. On the a ring choice “comfortable” is more important. A bollock may escape with just a cocktail ring but the cage limits the space further. it’s unlikely to escape with the cage.. The gap between the cage is an important measurent for this reason.
    Pain is never a good sign.
    I went from a cb 6000 to a cb6000s and then to a mm jb. I found the sizing from the cb useful when ordering the jb. So far the most I’ve done in it at one go was 5 weeks. I’m currently 3 weeks in to a lockdown. Everything is comfortable but I still get ” ring sting ” from time to time.

    1. My escaped ball occurred with the cage on. It wasn’t the JB, but a Chinese cage. However, it was clear that the 2′ ring was too big. I agree that comfort is the key. Most of the time I am completely unaware that the JB is on me. It should never, ever hurt. My cage is on 24/7. It would be impossible trying to live with a bad fit the rest of my life.

  11. What do you recommend for men with large balls? Hubby has a 2 inch cock ring now, actually slightly larger and no way I could sneak a natural fingernail between the metal and his sac. Only thing I’ve found is the leather adjustable.

    Also, a correctiOn. Yes, it’s possible for a man’s girth to doubLe. The one we bought is 6 inches around and he fills it flaccid.. even attempting erection he easily spills out the open deeign.

    I have looked at everything imaginable I think… but not ready to invest in custom yet

    1. Please reread the fitting section. It has all the information you need. You may have no choice but to get a custom cage.

  12. “If you get a base ring that keeps your balls in front of it and is comfortable to wear, you have it right.”
    I ordered a Holy Trainer after researching different cages. Rover has been wearing it for a week today and is loving the comfort of it.
    We are planning on getting him a metal cage as soon as we can. Thanks for the information. I am enjoying reading your blog.

    1. Has he worn the Holy Trainer for long? How does he keep it odor free?

  13. I sent you a comment several days ago and have not received a response . . . did I do something wrong or have you just not have time to consider it.

    1. I don’t generally reply to fitting questions. I think this section provides as much information as I have. Also, if you have a specific question that isn’t of general interest, use the Contact Us section to send a private message. I won’t guarantee that I will answer every message, but I do my best.

  14. Please help, my husband and I have just started to use chastity devices we started off with a metal one but that wasn’t comfy to sleep in so we went for a silicone one, my main question is when we put the cage on when he is flaccid it looks perfect t but then as he starts to try and get a erection the device will end up about 2 inches below where we started. As if it’s pulling it down. Is that supposed to sit like that? Does it mean the ring size is too big? It bothers us that it moves so much when he tries to get erect. We’ve tried putting ties around the cage then around he’s waist to hold it in place but then he’s cock still sticks out the side when trying to get erect. I hope I made that clear. Please help we are begginers and wany to get this right.

    1. Silicone devices tend to have issues with fit. The base ring or the tube are too large. This allows the movement. If you are serious enough, get a custom stainless steel chastity device like the Jail Bird. If you are testing, you may need to try several off-the-shelf cages to find a close fit.

  15. Thanks for all the helpful information on correct fitting above. We are just starting out along this path after many hours searching out as much information as we could and then filtering out the wheat from the chaff. As yet we have not finally decided on what device to go with however we have decided that it will be a cage with the cum through penis plug. After many measurements, I am just starting day 3 wearing a 44mm cock ring which I find is snug fitting and comfortable with all my tackle enclosed. In fact I do not realize I have it on unless I think about it. The one thing I have noticed though, my balls and scrotum have increased in size slightly and feel slightly heavy. Not uncomfortable though. Is this something that happens in the early stages when starting with chastity devices or is it just my mind over excited in the back ground as I also note I appear to be in that semi erect state 1/4 to 1/3 of am erection most of the time. I am planing on wearing the cock ring for at least a week to make sure that everything is fitting correctly as we would like it to be right the first time especially as it looks like we will have to go the custom made device to get exactly what we want.
    Thanks Peter

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