Collar fit is the most-asked question in BDSM accessory purchases. Sizing wrong produces either a too-tight choke or a sliding-around piece that doesn't feel right.
How to measure
- Use a soft tape measure (or a piece of string + a ruler).
- Stand normally, not stretched up; not hunched.
- Wrap around the base of the neck where the collar would sit. For most collars: at or just below the Adam's apple at the front; higher at the back.
- Note the circumference in cm.
- Don't pull tight, measure as if a comfortable necklace would sit.
Add comfort allowance
To the measured circumference, add:
- +1-2cm for collars worn briefly during scenes.
- +2-3cm for day collars worn for extended periods.
- +3-4cm for collars worn 24/7, must allow normal movement, swallowing, speaking.
UK adult neck sizes (rough averages)
- Smaller adult neck: 30-34cm circumference.
- Average adult neck: 35-40cm circumference.
- Larger adult neck: 41-46cm circumference.
For reference: standard UK shirt collar sizes 14-18 correspond roughly to 36-46cm.
Collar style affects sizing
Rigid metal collars (steel, brass)
- Posture collars, sized very specifically; need exact circumference + height clearance.
- Steel locking collars, sized precisely; once on, only the key opens.
- Order from a UK maker who takes specific measurements rather than off-the-shelf sizing.
Leather collars with buckle
- Forgiving sizing, buckle has multiple holes; adjustable across 3-5cm range.
- Choose so your measured neck size sits in the middle of the adjustable range, leaves room for tightening or loosening as needed.
Day collars (jewellery-style)
- Often sized like necklaces, 40cm, 45cm, 50cm standard lengths.
- Pick based on visible drop, 40cm sits at the collarbone; 45cm sits below; 50cm sits at the breastbone.
O-ring collars
- Standard wrap-style with adjustable buckle. Treat like buckle collars.
- The ring size is independent, 25mm, 35mm, 50mm rings; aesthetic choice not safety.
What's the right tightness
The two-finger rule applies to collars too:
- Two fingers should fit comfortably between the collar and the neck.
- Tight enough not to spin freely around the neck.
- Loose enough that swallowing is comfortable.
- No restriction of breath, collars should never affect breathing.
For prolonged wear
Day collars / 24/7 collars need to accommodate normal life:
- Normal head movement, turning, looking up, looking down.
- Eating / drinking comfortably.
- Sleep on different positions.
- No marking, extended pressure on the same point.
For 24/7 wear, looser fit than scene-collar fit. Some users size a full size up from their scene measurement.
What to skip
- Rigid metal collars without specific measurement, wrong-sized rigid collars are uncomfortable and difficult to remove.
- Nylon webbing collars, chafing, especially over time.
- "One size fits all" collars for specific BDSM use, rarely actually fit well.
- Locking collars without trying the fit first, too-tight locked collars are an A&E situation.
UK collar picks by type
- Bondage Boutique Day Collar range (£25-£60), leather; buckle adjustment.
- Liebe Seele Heritage (£45-£100), premium leather.
- Custom UK leather workshops (£100-£300), bespoke fitting.
- Etsy UK makers, many small UK leatherworkers offer custom collars.
See wardrobe of a quiet kink for collar aesthetic context.