If you’re brand new to chastity play or you’re a full time cage wearer it’s vitally important that you know how to correctly measure yourself so that you wear a chastity cage that fits you properly. Failing to do so can put your health and comfort at risk, which are both avoidable if you do this right from the start.

Chastity cage and ring measuring kit

At House of Denial we offer off the shelf devices, which means they’re produced in set sizes and designs. Unfortunately we’re not currently able to offer custom sizes, though they can be purchased from other sellers. If you’re a beginner or new to chastity it’s recommended that you buy an off the shelf device to make sure that you know chastity is for you and that you enjoy it. Custom cages are much more expensive, so knowing that you really want one before spending the money is advisable.

We sell cock cages in a large range of designs, materials and sizes. Some come with a number of back ring sizes so you can experiment with these to figure out which size fits you best. Plastic cock cages are generally lighter (depending on the design) than metal cages, but they’re usually not as durable and robust. With so many options it can come down to what you like the look of the most, or what your keyholder wants you to wear. The intention of this guide is to ensure you’re able to remain comfortably locked for as long as you or your keyholder wants you to be.

If you're more of a visual learner with the help of illustrator Soushiyo we've created a 4 part measurement guide comic, which will help you step by step through the same process that's listed in more detail below.

Before we dive into the best way to measure yourself you need to know what makes up a ball trap cage. All of our cages use a ball trap system, which holds your testicles between the back ring and cage to keep it in place.

Chastity cage and ring diagram

Now that you know what it looks like, let’s discuss the four most important measurements that you need to take:

  1. Back ring - Internal diameter (inside width)
  2. Cage length - Length of your flaccid penis
  3. Internal Cage diameter - The internal width relates to your penis girth
  4. Ball trap gap - The gap between the cage and back ring

How to measure the back ring

As I mentioned earlier, selecting the correct ring size for you is really important as a back ring that’s too small can cause you physical issues, which includes cutting off blood flow or the ability to urinate. Opting for a ring that’s too big will make it much easier to release yourself and will move around too easily, which could cause friction burns where the ring rubs against your skin.

Curved oval back ring demonstrating internal diameter measurement

To properly measure your ring size you’ll need the following items:

  1. Either a) a piece of thick string or b) cotton piping cord measuring at least 30cm / 12 inches in length. If you go for a cord try to find one that’s quite thick, ideally around the same thickness as the back ring you intend to buy, though one that’s slightly thinner will do fine. Neither should be stretchy and the material that you use needs to be rounded, not flat. Using a light material colour like white will make it easier to mark.
  2. A black marker pen with a fine tip. This will be used later to mark the string or cord.
  3. A flat 30cm / 12 inch ruler.

We highly recommend that you don’t use a flat measuring tape as they don’t sit properly against the contours of your body.

Place the end of the string or cord on the top of your penis and wrap it around and under your testicles until it meets at the top again. Loosely make a knot where the material meets and test the string to make sure that it’s not too tight or loose. You can check this by seeing how easy it is to put your little finger under the string. It should only just fit under the string with some tension. If you can easily hold your finger under the string you’ll need to tighten the knot a bit, or loosen the knot if it’s much too tight. Leave it in place for five minutes. If you start to see any discolouration in your cock or balls then it’s cutting off blood flood and the knot will need to be loosened. If you’re able to, go to the toilet and try to urinate. If there’s no issue there either you’re good to move onto the next stage.

Tighten the knot in the string that you made earlier, but only do this when you’re completely flaccid. At this point it’s really important that you forget about it. I know, it’s much easier said than done. You’re excited and might get aroused thinking about the shiny new chastity device you’re measuring for, but it’s precisely this that you need to put out of your mind, for the time being at least. You need to get on with your day and forget all about it, unless any issues present themselves. If you start feeling the string digging into you and cutting off blood flow then it’s too tight, so very carefully release the knot and make the length slightly bigger. Tighten the string a little bit if it starts sliding down, but only a tiny bit at a time.

Set an alarm for 15-20 minutes on your phone or ask your smart speaker to do it for you. This will give your body a little time to get used to it being tied around your cock and balls. If the alarm goes off after this amount of time and it feels comfortable then take your pen and mark the material at the edge of the knot. You can now cut the string at the point you marked it or untie it if you’re able to.

Place the length of string or cord along the flat ruler to get the ring circumference measurement. To get a more accurate measurement we recommend repeating this process at least 2 more times and at different times of the day. Due to temperature fluctuations over the duration of a day we’d suggest taking one in the morning, one at midday and one in the evening. This will give us 3 measurements that we can then divide by 3 to give you an average measurement.

Example: 141mm + 140.5mm + 142mm = 423.5 / 3 = 141mm

We can then take the average length measurement (in our example 141mm), which gives us the circumference. You then need to divide that by Pi (3.14):

Example: 141mm / 3.14 = 44.95mm

With that measurement you’ll have your ring size. Match that to the closest ring sizes available from our store.

We have three different ring types available on our store: Circular, curved/oval and curved hinged. 

Ring Types

3 different chastity back rings

Circular Ring

Probably the most common type of back ring. They’re a simple circle - some come with a gap at the top, while some others don’t. To put one on you need to push your penis and testicles through the ring.

Curved/Oval Ring

Similar to the circular ring that doesn’t have a break in it and you put your genitals through the hole to put it on, but the shape of these rings make them slightly longer, so there’s a bit more room at the bottom.

Curved Hinged Ring

The hinged rings open out, so you can place the ring under your ball sack then close the ring shut above your cock. These rings are much wider and have a smaller internal height.

One issue that some customers have mentioned with the rings that are hinged is that the small gap at the bottom of the ring can cause some pinching. We’ve heard from some users who cover this gap over with a small piece of body safe plastic or tape.

Choosing your back ring based on your measurements

We don’t currently offer custom ring sizes unfortunately, so you’ll need to match up your measurements to the closest ring size that comes with the device you’d like. Some of our chastity kits come with a full range of ring sizes, so you’ll be able to experiment with the different sizes until you settle on the one that fits you the best. You can also change rings depending on the climate or temperature of the environment that you’re in.

Most of our stainless steel chastity cages come with one back ring, so we recommend measuring yourself properly. Be patient and do it right the first time. If you’re between sizes and would like to order a second ring with your device you can order a new back ring here.

Here are some top tips when you select your ring(s):

  1. If you’re a beginner to chastity we recommend selecting the larger ring if you’re between sizes. For example, if you measure 48mm go for a 50mm ring instead of a 45mm ring. You can always buy a smaller 45mm ring from us later once you’ve become more used to wearing a chastity cage.
  2. If the weather or your environment is slightly colder then your penis and scrotum will tighten, so opt for the bigger ring size.
  3. When you’re in a warmer climate you’ll naturally be slightly larger, which is the best time to use a smaller back ring.

Don’t panic if you don’t get your ring size right the very first time. We’re here to help if you need a larger or smaller ring. Simply let us know and we’ll go through your options with you.

How to measure the chastity cage/tube length

I want to address one issue before you begin measuring your penis to fit perfectly into a chastity cage. We’ve seen countless pictures of guys or sissy girls wearing a chastity device that displays a clear gap between the tip of their penis and the end of the cage. This offers room for you to get erect or grow into. This is something you absolutely should avoid. It entirely defeats the point of being locked in chastity, so with this guide you should be able to measure and wear a cage that fits very snuggly on your cock.

Honesty at this point is also a must. In order to accurately measure your penis length you’ll need to be completely flaccid. No plumping, stretching or stimulated swelling will be helpful and will produce inaccurate measurements. Don’t take a warm or ice cold shower before measuring yourself as they’ll change your penis size by enlarging or shrinking your dick. Relax, be honest with yourself and follow these instructions:

  1. While standing upright and ensuring that you’re completely flaccid take a 30cm / 12 inch flat ruler and place it against your pubic bone and lie it flat on top of your penis. You need to measure from the base to the tip of your penis. Write down that measurement.
  2. To make sure your cage fits properly it’s generally recommended that you subtract 6mm / ¼ inch to 12mm / ½ inch from that measurement. This will ensure that the cage is a good, tight fit.

That’s it! We totally understand that all of this touching can get arousing (been there!) but you need to do your best to keep focused on the task in hand (so to speak) and only measure yourself when you’re completely flaccid.

One last thing before we move on. If you’ve not worn a chastity cage before you’ll need to get used to urinating sitting down, but the necessity to do that can be minimised. Having a cage that fits properly with no space at the end will allow you to more easily align your urethra with the hole at the end of the cage, which will make pissing much easier and far less messy. It will also keep you cleaner for longer.

Measuring the cage/tube internal diameter

This is super easy as we’ve already done something similar when taking the measurement for the back ring. Instead, we’re going to measure the girth / circumference of your penis.

Again, this measurement needs to be taken when you’re completely flaccid, so relax, focus on something else that won’t get you aroused and follow these instructions:

  1. Cut a length of thick white string and wrap it around your cock at its thickest point. We recommend doing this about half way up the shaft.
  2. Mark the string with your pen being careful not to draw on your penis.
  3. Place the length of string against your ruler to get the circumference.
  4. Repeat the process and another 2 times at different points during a day. Add these measurements together then divide them by 3 to get your average girth.
  5. Divide this measurement by 3.14 to give you the internal cage diameter.
  6. Make a note of the number for when you select your cage.

Ideally you should fill as much of the cage as possible so that it fits like a glove. You don’t want to give yourself too much (if any) room for your cock to expand or grow into the cage, so have this in mind when making your selection.

The Gap - The space between the cage and ring

With all ball lock chastity devices there’s a gap of varying size between the cage section and the back ring. This is known as “the gap”.

There’s a simple formula to work out if you should look for a wider or smaller gap:

High and Tight = Wider gap
Low and Loose = Smaller gap

Essentially if your testicles hang quite high up and are tight to your body you should look for a wider gap. If your balls hang low with plenty of skin making up your ball sack then you should look for a smaller gap to trap you between the cage and ring.

Over time as your body adjusts to long term chastity cage use it’s not uncommon for you to need a smaller gap. This is due to your balls starting to hang lower underneath the cage, which requires a smaller gap to keep you firmly in place.

Don’t go for a gap that’s too small as that can cause medical issues including cutting off blood flow. This is going to make you uncomfortable, which a well fitted cage shouldn’t do.

Personal Cage Preferences

That’s everything that you’ll need to measure and buy a chastity cage, but before we finish I want to touch on a few other points that are worth considering. These come down to your own personal preferences.

Lock Type / Mechanism

Our chastity devices come with two different lock and key types: a sliding barrel lock or a padlock.

The sliding barrel locks that come with the Holy Trainer and many of our metal cages allow the cage design to have a lower profile (this will make it less obvious when the kit is worn under clothing) and more discreet. These hidden locks don’t make a sound when you move around as they don’t clang against the cage.

Padlocks are excellent if you love the aesthetic look of a lock attached to your cage. The psychological impact that seeing the padlock locked to the cage is also very important not only for submissives, but for keyholders too. They can be annoying though as they ping off your cage when you move, but this can be eliminated if you wrap an elastic band around it or tape it down.

Colour/ Color

Chastity cages in 4 different colours

At House of Denial we offer a selection of chastity devices in different colours. Clear, black and pink cages are very popular in our plastic and silicone devices, while shiny stainless steel is only available in our metal cage collection.

We also have some other colours including red, blue, purple and yellow in a small number of cages.


If you have any questions regarding your size please don't hesitate to get in touch with us via the contact us page. By following this comprehensive guide correctly you should be able to identify the correct cage and ring size for you, but if you still need any help please do send us a message and we'll get back to you as soon as possible.

If you think we've missed anything important from this size guide please let us know. The chastity community is full of very knowledgeable people based on significant personal experience and we're very open to listening to ideas or suggestions that will allow us to improve this page.