What Is a 3/4 Helmet? | Skull Coverage, Chin Exposed

A 3/4 helmet covers the top, sides, ears, and back of the head but leaves the entire face and chin exposed — it protects roughly 55.5% of crash scenarios against traumatic brain injury.

If you ride a motorcycle and want more coverage than a half helmet but can’t tolerate a full chin bar, the 3/4 is your middle ground. Also called a jet helmet or open-face model, it wraps the skull in impact-absorbing EPS foam under a hard shell, then stops at the cheekbones. That trade — head protection without facial cage — is what every buyer needs to understand before strapping one on.

What Exactly Does a 3/4 Helmet Cover?

The shell and inner liner extend down the sides of the head past the ears, curve around the back of the skull, and cover the cheeks. You get the same crown and side protection as a full-face helmet — the EPS liner absorbs crash energy the same way — but nothing protects the jaw, teeth, chin, or lower face. A small snap-on visor or windscreen may deflect some airflow, but it won’t stop impact debris or prevent facial contact with the pavement.

The protection gap matters in numbers. That’s better than the 36.8% of half helmets but still well below what a full-face model offers when facial impact is involved. Every standard — DOT, SNELL M2020, ECE 22.05/22.06 — tests for impact absorption and retention, not chin-bar presence.

Shell Materials and Safety Standards

Shells come in three grades. ABS plastic is the budget standard: stiff enough to spread impact load but heavier. Polycarbonate is lighter and more impact-resistant per gram; fiberglass composites split the difference on weight and cost. Premium models use carbon fiber for minimal weight and high stiffness.

Inside every approved 3/4 helmet sits a multi-density Expanded Polystyrene liner — that’s the foam that actually crushes on impact to decelerate your head. Modern manufacturers shape these liners with CAD software to optimize aerodynamics and distribute impact force across the most protective geometry.

DOT (FMVSS 218) is mandatory in the US; SNELL’s M2020 standard is voluntary and tougher. ECE 22.05 and the newer 22.06 govern Europe and are recognized globally; some riders prefer ECE for its rotational-impact testing. FIM is the new track-and-racing standard. SHARP is a UK star-rating system that tests more than the minimum.

If you’re ready to check current models with verified safety ratings, our tested roundup of the best 3/4 helmets breaks down which shells and liners actually perform.

How to Fit a 3/4 Helmet Correctly

The same fit rules apply to open-face as to full-face, with one extra caution: without a chin strap holding the jaw, roll-off risk is higher if the fit is loose. Measure your head circumference one inch above the eyebrows. The helmet should go on snug — you shouldn’t be able to slide it side-to-side without moving your head — but no pressure points on the crown. Quality EPS liners compress 10–15% during break-in, so what feels firm at first will settle.

Snug and precise: Cheek pads should contact your cheeks firmly. The helmet’s front edge must sit one inch above your eyebrows, not higher. Once the chin strap is fastened — with one finger’s gap under your chin — do a roll-off test: push the helmet backward from the crown; it should move no more than a quarter inch. Real riders recheck strap tension after 15 minutes on the road, because liners settle and straps loosen.

Fit also means matching your head shape. If the helmet rocks front-to-back or pushes at the temples, you’re in the wrong shape category — Round Oval, Long Oval, or Intermediate Oval. A 3/4 that doesn’t match your skull shape will never protect properly, no matter how tight you crank the strap.

Common Fit Mistakes

• Confusing 3/4 coverage with half-helmet coverage — a 3/4 extends lower behind the ears and wraps the back of the skull; a half helmet stops above the ears.
• Relying on the flip-up visor for face protection — it helps against bugs and wind, not crashes.
• Assuming all 3/4 helmets fit the same head shape — shape mismatch is the top reason a perfectly sized helme still slides around.