Cock ring size guide: how to measure and what size to buy

Why the size matters

A ring works by gently slowing the flow of blood out of the penis, so it needs to be snug. A ring that's too loose slips and makes no difference. One that's too tight pinches, can cause numbness or bruising, and is hard to get off, which is the part that matters most.

UK urologists say a constriction ring should never stay on for more than 30 minutes, because longer can cause damage. A ring that fits well is easy to take off well before then.

How to measure in two minutes

• Take a piece of string, a shoelace or a thin strip of paper. A soft tape measure is easier if you have one.
• Measure while soft or only slightly firm, because that's when you put a ring on.
• Wrap it around the base of the shaft, where the ring will sit. Snug against the skin, not pulled tight.
• Mark where it overlaps, lay it flat along a ruler and read the length in centimetres. That's the circumference.
• Divide the circumference by 3.14 to get the diameter. Multiply by 10 to turn centimetres into millimetres, which is how ring sizes are listed.

From measurement to ring size

Inner diameter is the width of the hole across the middle, unstretched. It's the number to compare with your measurement.

• Rigid rings need to match your measurement closely, within a few millimetres.
• Stretchy rings are listed at their resting size and stretch well beyond it. A stretchy ring with a 30 mm inner diameter isn't meant for a 9.4 cm measurement: it's made to stretch over most men.
• Between two sizes? With a stretchy ring, either will do: the smaller one holds more firmly. With a rigid ring, choose the larger one, because you need to be able to get it off.

Stretchy, adjustable or rigid

• Stretchy rings, in silicone or TPR, fit the widest range of sizes and roll off easily. The best first ring for almost everyone. Thicker rings give a firmer hold than thin ones.
• Adjustable rings fasten with a toggle, snaps or a strap, so you set the fit yourself and can loosen it in a second. The JoyRings strap ring is a 12 cm silicone strap with a sliding toggle. Good if you're between sizes.
• Rigid rings, in metal or hard plastic, can't stretch. They have to go on while soft and must match your size closely. Leave them until you know your size and have worn a stretchy ring a few times.

Where it sits changes the size

Worn around the shaft only, a ring needs to fit the base of the shaft. Worn behind the testicles as well, it needs to go around both, which takes a much bigger ring: measure around both, at the point where the ring will sit.

Start with the shaft only. It's easier to put on, easier to take off and easier to judge.

Checking the fit

• Right: snug and firm, with no pinching, and it rolls or slides off with a little lube.
• Too tight: it leaves deep marks, pinches, or the skin feels cold or numb or changes colour. Take it off straight away and size up.
• Too loose: it slips down or makes no difference. Size down, or try an adjustable ring.
• A pack of three sizes is the cheapest way to settle it. Try each and keep the one that feels right.

Safety rules, whatever the size

• Take it off after 20 minutes. Never go past 30.
• Never sleep in a ring, or wear one when you've been drinking heavily and might forget it's on.
• Use a little water-based lube to put it on and take it off.
• If you take blood-thinning medicines or have a blood or circulation problem, check with your GP first. UK urologists advise caution with vacuum devices and their rings for people on blood thinners.
• If a ring won't come off, don't force it. Call 111, or go to A&E if it's painful or the skin is changing colour.
• An erection that lasts more than 3 to 4 hours is a medical emergency. Call 999 or go to A&E.

Questions

This guide is general information, not medical advice. If something hurts or worries you, stop and speak to a GP or pharmacist.

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