Guides

Chastity cage sizing: how to measure, size charts and your first cage

A chastity cage fits on three numbers: the inner diameter of the base ring, the length of the cage, and the gap between them. Get the ring right above all, because it's the one part that can never be adjusted, and it's the part that causes harm when it's too tight. Most buyers end up somewhere around a 45 mm ring, and almost every maker sizes the cage to your smallest flaccid length, not your average. This guide walks through how makers tell you to measure, why they disagree, how to read a size chart, and how to buy a first cage you won't regret. For the different designs, see chastity cage types; for what can go wrong, our safety guide.

The three numbers that decide the fit

The base ring sits behind the scrotum and holds everything in place. It's sold by its inner diameter in millimetres. The cage, or tube, covers the penis and is sold by length, sometimes with a width option too. The gap, often called the ball gap, is the space between ring and cage, usually set with small spacers.

A 2023 US patent for a chastity device puts it plainly: ring size and spacing are the two most important adjustments. That matches what makers say. Length is the comfort number, the gap is the fine-tuning number, and the ring is the safety number. Mature Metal, a stainless steel maker, warns that a ring's inside diameter "can never be adjusted", while a wrong gap is "an easy fix".

Measuring for the ring

This is where makers openly disagree, and it's worth knowing that before you trust any single chart.

Holy Trainer, a Swiss maker of resin cages, publishes a string method. You tie a non-elastic string about 30 cm long around the base of the scrotum and penis with a double knot, snug enough that you can't slip a finger under it, wear it for five minutes, then cut it and measure its length. Their chart turns that length into a ring size, and they say most of their customers use the 45 mm ring.

KINK3D, a US maker of 3D-printed cages, takes the opposite view. It says it doesn't recommend measuring for the base ring with a tape measure or string at all, because a tape "can often give a false sense of confidence" and lead to a ring that's much too large. Its advice is to try real rings, starting from the middle of its range rather than jumping to the very smallest or largest sizes. A community writer who sells his own cages goes further and calls the string method "the most ridiculous" way to size a ring, preferring to wrap a strip of paper around the flaccid shaft, mark it, and divide that circumference by pi to get a diameter.

What to take from the argument: a string or paper measurement gives you a starting point, not an answer. The only reliable test is wearing a ring for a while. That's why sizing kits and cheap multi-ring cages exist, and why Mature Metal sends customers plastic sizing rings before it makes anything in steel.

Measuring for length

Measure when you're flaccid and at your smallest, never straight after a hot shower. KINK3D's guide for its Cobra cage says to measure along the top, from the base to the tip, with a cloth tape or string, and to do it several times. Community guides add that you should hold the penis parallel to the floor rather than letting it hang, because hanging adds length.

Then go shorter. The common rule is a cage 10 to 20 mm shorter than your smallest flaccid length. Mature Metal subtracts a quarter of an inch from your shortest reading, and KINK3D says that when you fall between two sizes, most people prefer the shorter one. A cage that's too long lets you slide forward and pulls on the ring; one that's a little short simply holds you snugly.

The ball gap

Mature Metal is refreshingly honest about this one: there's "no good way to measure" the gap. Most of its customers choose 3/8 of an inch, people with a looser, lower scrotum often go down to a quarter of an inch, and people with a tight, high scrotum may need half an inch. Off-the-shelf cages usually come with spacers that set a gap of roughly 10 to 14 mm, so you can adjust it at home. If the cage pinches skin between ring and tube, the gap is too small; if things can slip out, it's usually too large or the ring is.

Growers and showers

A grower's penis gains a lot of length on erection; a shower's looks much the same size soft or hard and gains less. The only study that defines the terms, published in the International Journal of Impotence Research in 2018, used a change of 4 cm as the cut-off. Of 274 men examined at a clinic, 26% were growers, gaining an average of 5.3 cm, and 74% were showers, gaining 3.1 cm.

That study wasn't about cages, so take this as practical inference rather than research: because cages are sized to your smallest flaccid length, growers have the largest gap between the cage and an erection, and feel more pressure at night. One community writer says a grower has "no way" to wear a steel cage without straps. If you know you're a grower, a cage with a little more room and a design that holds well, plus a slow start, makes more sense than the tightest fit you can find.

Ring sizes across makers

Size charts look different, but they cover a similar range. KINK3D sells eight rings measured by inner diameter, from 38.1 mm to 60.3 mm in steps of about 3 mm. Holy Trainer's chart runs from 36 to 60 mm. The CB-6000 kit comes with five U-shaped rings, which one retailer lists from 1.5 to 2 inches, and those rings don't swap with the older CB-3000 or the Curve. Retail listings give the CB-6000 cage a length of 83 mm, with the shorter CB-6000S at 64 mm.

Don't assume one maker's 45 mm feels like another's. Ring shape matters: a full round ring, a U-shaped ring and a curved or angled ring sit differently against the body, which is why our types guide covers ring styles in detail.

Buying a first cage

A first cage is a measuring tool as much as a toy. One community writer's advice is to filter plastic listings for cages with four or more rings at around 35 dollars or less, wear it, and learn your real sizes before spending more. His own first 60 dollars of cages lasted "not quite six weeks", and he says few people settle on a long-term cage for under 200 dollars. On Mature Metal's site in October 2026, featured steel items ran from 125 to 310 dollars, and the same writer puts a made-to-measure steel cage at 350 to 400 dollars. Prices change, so treat these as a rough map.

Marketplace listings on Amazon, AliExpress and similar sites are where most cheap cages are sold, often the same mass-produced designs under many names. That's fine for a test cage, but read claims carefully. In the US, sex toys are classed as novelties, so labels such as "medical-grade" are the seller's own words, not a certified standard. Check the return policy before you order, too: KINK3D, for one, doesn't exchange sizes and points customers to a second-hand forum instead.

For the first cage itself, choose a non-porous material that's easy to clean, several ring sizes, and a lock or numbered plastic seal that can be released fast. Then build up wear time slowly, as our guide to chastity training explains, and decide where the key will live; our page on chastity key safes and lockboxes covers that.

Upgrades, resizing and second-hand cages

Once you know your numbers, upgrading is easier. Steel makers can usually change the gap or the length; the ring diameter is the part that has to be right from the start. Second-hand cages are cheap but need care. General sex-toy hygiene guidance says non-porous materials such as steel, ABS plastic and silicone can be sanitised, while porous ones can only be cleaned. KINK3D prints in PA12 nylon, which is porous, so a used printed cage is the hardest to trust. Never share or buy a cage that's been worn during an active infection, and replace any cage with cracks, rough edges or a ring that's warped.

Support bands, and when a ring is too big

A support band is a strap, usually elastic, that holds the cage up and in place. It's the standard fix when a ring is too large to hold a cage on its own, and some growers use one by choice. The same community writer prefers to avoid straps, saying they "introduce so many issues themselves", from rubbing to trapped heat. A better-fitting ring is the first fix; a band is the backup.

One rule beats every chart: if you see swelling, colour change, numbness or pain, the cage comes off at once, whatever the size guide said. Our chastity cage safety guide lists the warning signs and what to do if a device gets stuck. This page is practical guidance, not medical advice. Once the fit is right, the interesting part begins: the strip at the top shows women live now who list chastity, tease or denial, and our chastity cams page explains how online keyholding works.