Chastity Size Guide - Measuring For A Perfect Fit

Posted by Mistress Scarlett 02/09/2016 5 Comment(s) Chastity Guides,

Many chastity wearers try many devices until they find the perfect fit. It is therefore important and less costly to understand the size of your penis and the measurements of chastity devices. Chastity device sizes can be broadly broken into the following three categories.




Penis sizes vary in length quite considerably when fully erect. It is however important to know the length of your penis when you are soft. By soft I mean completely un-erect. Not the length when you are semi erect but your normal penis length when not aroused, not hot and not cold. As a general rule of thumb, you should look for a device which is 1/4 to 1/2 of an inch smaller than your soft penis size. This is because not all chastity devices are worn the full length of your penis. The smaller size allows for the ring mechanism. It is also important to consider what you are looking for from a chastity device. Are you looking for chastity device which can be worn for longer periods of time or are you looking for a device which is perhaps a tighter fit and will help you fulfil your fantasies whilst playing?


Ring Size


The second most important size is the size of the ring. The ring attaches to the chastity device or cage and runs around the base of your testicles. The image below will help you understand how you can measure yourself to find the correct ring size. This size can be a little tricky to measure however fear not because all of our devices have spare rings available to ensure you can find the perfect fit. This measurement provides you with a circumference measurement. You need to convert this to find the diameter, which is the measurement our rings are available in. Here is a list of ring sizes and their equivlient circumference:-

chastity size guide


Ring Size Diameter - Circumference


Ring Size 38mm = Circumference of 119mm


Ring Size 41mm = Circumference of 129mm


Ring Size 47mm = Circumference of 148mm


Ring Size 50mm = Circumference of 157mm



Again you need to consider whether you are looking for a tight fit, or something a little more comfortable. It goes without saying that you don't want the ring to be so tight that it cuts off blood flow to your member. It must also not be too loose to allow you to escape and cheat. Many chastity wearers will try two or three chastity ring sizes before they find the perfect fit. Depending on the device you have we offer four types of spare rings in various sizes. Please contact us if you need any assistance.


Girth or Width


Most chastity devices are similar in girth. The girth is the measurement of the cage in which you insert your penis. Many chastity wearers do not really need to consider this measurement but if you are particularly thick then you may want to consider s custom made chastity device. However this is not the case for 95% of us. Most chastity devices provide a cage diameter. The chastity cage diameter is the measurement which relates to the girth (width) of your penis.


At Toys 4 Naughty Boys, we provide you all the sizes of our chastity devices and chastity cages on each product page. If you have any queries, or need any assistance at all we are here to help. We have been selling chastity devices for years and we are not prudish. Don't be shy we are sure it has been asked before, drop us a line with any queries you may have.

5 Comment(s)

10/11/2016, 02:26:12 PM

Could I have some help with ring fitting on your chastity devices please? Using your guide I measured about 200mm Since sizes end at 50mm, and I know I'm not massively well endowed, I therefore assume that either the guide, or my measuring technique, is way off.

Mistress Scarlett:
11/11/2016, 12:24:03 PM

200mm is the circumference measurement, you need to convert that to find the diameter and the appropriate ring size. 200mm is a big measurement, but I'd suggest you try a 50mm ring and see how that goes.

Aphrodite's slave:
01/05/2017, 02:31:23 PM

I'm a proud wearer of a t4nb device since some months and I had that same problem. I'm on the lower average, but when erect my penis base measure up to a diameter of 50mm. Anyway, your fully erect size is not the measurement you need. That because the device won't allow your penis to become fully erect, the base will not reach her biggest size too. At least, thats how my penis work. I purchased a device with a 47mm ring, even if measuring 50mm when fully erect, but still it wasn't small enough. Fact is that this ring kinda squeezes my cock when i wear it alone and I'm fully erect, but feel like a wide ring when I wear my device, so I'm going to orders a smaller measure soon. My suggestion is that you need at least half centimeter less than you measure when your cock is free. Hope this being useful to next customers (and maybe helps t4nb, which makes such good devices, to improve this size guide too)

Mistress Scarlett:
17/09/2017, 12:24:59 AM

Hi, thanks for the comments and we hope they really help other wearers. Everybody is slightly different in their sizing requirements and comfort level so its all about trying and finding what works best for you.

15/07/2017, 09:27:40 AM

I read the directions for measuring the circumference of my cock in mm but I didn't measure up to the ring size. Please explain in detail how to find it what's the math steps to getting the correct answer Sincerely Mattie

Mistress Scarlett:
17/09/2017, 12:29:24 AM

Hi Mattie, thanks for the comment, please send us an email and we can help you find the size you need.

16/08/2017, 08:14:02 AM

I'm running at 26cm circumference. That's like 260mm. I used the largest ring I own and I have blue balls. In the literal sense. This is frustrating. Any help!?

Mistress Scarlett:
17/09/2017, 12:28:50 AM

Hi Rob, 26cm seems a very large measurement, you are either a very very big boy or perhaps have made a mistake with the measurement. The circumference is the measurement around your ball sack. If you imagine a using your fingers to create a circle, the measurement is around the outside of that circle. Hope that helps.

Jack sinclair:
30/01/2018, 11:15:24 PM

I have had a few different chastity devices but struggle with the fact I have one ball. Cub smaller than the other. The small one often slips back through the ring and then whole thing becomes loose. I’ve tried a smaller ring but it causes too much discomfort and swelling. What can I do?

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