Cock Ring Size Guide: How to Measure Safely

Updated October 2026

Quick answer: measure the erect girth at the base of the penis with a soft tape, then divide by 3.14 to get the inner diameter. A 120 mm girth, for example, means about 38 mm, so start with a stretchy ring of about 34 to 38 mm. A ring should feel snug, never tight, and come off after 20 to 30 minutes.

A cock ring should feel snug, never tight. Getting the size right is the difference between a ring you enjoy and one you take off after a minute, and it matters for safety too. This guide shows how to measure at home, how stretchy and rigid rings differ, which sizes to start with and how long to wear one. For what rings do and how to use one, read our cock rings guide.

How to measure

Use a soft tape measure, or a strip of paper and a ruler.
Measure the girth (the distance around) at the base of the penis, where the ring will sit. Measure when erect for the fullest size, and note the soft size too.
To turn girth into diameter, divide by 3.14. The table below does it for you.
For a ring worn around the testicles as well, add a little room; stretchy rings are the easiest way to do this.

Erect girth	Diameter	Start with an inner diameter of
100 mm (10 cm)	about 32 mm	a stretchy ring of about 28 to 32 mm
110 mm (11 cm)	about 35 mm	a stretchy ring of about 31 to 35 mm
120 mm (12 cm)	about 38 mm	a stretchy ring of about 34 to 38 mm
130 mm (13 cm)	about 41 mm	a stretchy ring of about 37 to 41 mm
140 mm (14 cm)	about 45 mm	a stretchy ring of about 41 to 45 mm
150 mm (15 cm)	about 48 mm	a stretchy ring of about 44 to 48 mm

These are starting points, not rules. Bodies differ, and stretchy silicone gives a lot of room either way.

Stretchy vs rigid rings

Stretchy rings (silicone or TPR) stretch to go on and off, so one size fits a wide range of bodies. They are the right choice for a first ring, and every ring we stock is stretchy.

Rigid rings (metal, hard plastic) have a fixed size and can be hard to remove if swelling happens. We do not stock them, and we suggest skipping them unless you have measured carefully and have experience.

Starter sizes and when to size up

Start stretchy and a little loose. A ring that slides on easily when soft and feels snug when erect is about right.
Size up if the ring leaves a deep mark, feels tight within the first few minutes, or is hard to roll off.
Size down only if it slips off with no feeling at all, and only with a stretchy ring.
Adjustable rings with a loop or a toggle let you fine-tune the fit.

Sizes of the rings we stock

Sizes as stated by each maker, at the time of writing. Where a maker gives only the outside dimensions, the inner size is marked as not stated; all of these rings are stretchy.

Ring	Stated size	Inner diameter	Material
Double Ring Silicone 37/45 mm	Two rings	37 mm and 45 mm	Silicone
Tear Silicone Ring 50 mm	112 x 63 mm outside	50 mm	Silicone
Vibrating Cock Ring Love Dolphig Ring Pink	36 x 66 mm	Not stated	Not stated
Exciting Ring Rabbit Vibrating Ring	92 x 44 x 24 mm	Not stated	TPR
Vibrating Penis Ring USB Silicone	110 x 47 mm	Not stated	Silicone and ABS
Vibrating Penis Ring Vibrant Penis Ring I	113 x 56 mm	Not stated	Silicone
Kenny Penis Ring with Clitoris Stimulator and APP Night Blue	66 x 66 mm	Not stated	Silicone
Ringo Vibrating Ring with App Unibody Black	83 x 83 mm	Not stated	Liquid silicone
Darkblack Vibrating Ring with Led Remote Control USB Silicone	94 x 35 mm	Not stated	Silicone

How long to wear one, and safety

Take it off within 20 to 30 minutes. Never sleep in a ring.
Remove it at once if you feel pain, numbness or coldness, or if the skin changes colour.
Use water-based lube to put it on and take it off; see our lube compatibility chart.
Ask a doctor first if you have a blood-circulation condition or take blood-thinning medicine.
Never force it. If a ring will not come off, stay calm, use more lube and ease it off; seek medical help if it still will not move.