How To Fit a Motorcycle Helmet

A motorcycle helmet only protects you if it fits. A lid that is too loose can shift or lift in a crash, and a poor shape match creates pressure points that turn a great helmet into a headache on a long ride. Getting fit right comes down to two things working together: your head's circumference (the number) and your head's shape (the geometry). This guide walks you through both, gives you the official SHOEI and HJC size charts, shows you how a correct fit should feel, and — the part most shoppers actually want — tells you which of our helmets tend to fit alike so you can shop with confidence.

Step 1 — Measure your head

Grab a soft, flexible cloth tape measure (not a rigid steel one). Wrap it horizontally around the largest part of your head — about 1 inch (2.5 cm) above your eyebrows in front, above your ears on the sides, and around the fullest point at the back. Keep it level. Slide the tape up and down slightly and take the reading two or three times, then use the largest measurement. This is the method SHOEI, HJC, Bell, Icon and NHTSA all specify.

Write down the number in centimeters — helmet charts are built around cm, and as you'll see below, the letter sizes are not identical between brands.

Step 2 — Know your head shape

Two people with the exact same circumference can need different helmets, because heads aren't round — they're ovals of different proportions. The industry (and U.S. safety authority NHTSA) sorts them into three internal shapes:

• Round Oval — front-to-back is nearly the same as side-to-side (a rounder head).
• Intermediate Oval — slightly longer front-to-back than side-to-side. This is the most common shape among North American riders, and what most street helmets are built for.
• Long Oval — clearly longer front-to-back, with narrower sides.

How to find yours: have a friend take a photo looking straight down at the top of your head (or use a mirror above you), with your hair flattened. Look at the outline of your skull — is it round, or clearly longer front-to-back? — and match it to one of the three shapes above.

Step 3 — Read the size chart (SHOEI vs HJC)

Match your centimeter measurement to the chart for the brand and model you're considering. Note that the two brands do not label sizes identically — this is the single most important thing to check before you assume a size.

SHOEI size chart

HJC size chart (general)

HJC also offers 3XS (50–51) and 4XL–5XL (66–69 cm) on some models. A few HJC models (for example parts of the i-series and C-series) use a slightly shifted chart where L is 59–60 and XL is 61–62 — so always confirm against the specific helmet's own size chart.

What if I'm between two sizes?

Start with the smaller of the two. Helmets loosen slightly as the comfort liner — mostly the cheek pads — beds in with use, so a new helmet should feel snug. SHOEI's own guidance is to try the smaller size first and use the chart only as a starting point. If it's genuinely painful (not just firm), size up or switch to thinner cheek pads.

Step 4 — The fit check

When you first put a correctly sized helmet on, it should be a bit of work to pull down past your ears, then settle in snug and even. Run through this quick check:

• Even all around. Firm, uniform contact on your forehead, sides and cheeks. No single hot spot.
• Cheeks. The cheek pads should press your cheeks (you may look slightly "chipmunk" at first — that's correct, and they relax with use).
• Skin, not slip. Put your hands on the helmet and rotate it side-to-side and up-and-down. Your skin and eyebrows should move with the helmet. If the helmet slides over your skin, it's too big.
• Shake test. Shake and nod your head briskly — the helmet should stay locked in place.
• Roll-off test. With the strap fastened, try to roll the helmet forward off the back of your head. It should not come off.
• Wear it 20–30 minutes. Some pressure points only show up after a while. A red forehead line, aching temples, or ear pain mean it's the wrong size or shape — trust that, don't "tough it out."

SHOEI vs HJC — how they fit

Each brand builds to a house interior shape, which is why models within a brand tend to fit alike:

• SHOEI builds virtually its entire U.S. range to an intermediate-oval interior, and uses multiple shell sizes across the range for a proportional, near-custom fit. If you're a classic intermediate-oval head, SHOEI usually feels "made for you."
• HJC tends to run rounder / more neutral — a touch rounder than SHOEI. If you have a rounder head, or you felt side/temple pressure in a SHOEI, HJC is often the more comfortable shape (and vice-versa: forehead pressure in an HJC points you toward SHOEI's more oval interior).

Manufacturers generally don't publish a per-model head shape, so treat these as brand-level tendencies, confirmed by your own fit check.

"If this fits you, start here" — our helmets by fit family

Because each brand is consistent internally, your known size in one model is a reliable starting point for another of the same brand — then confirm with that model's size chart and a fit check. Below are the helmets we carry, grouped by type so you can jump from one you love to a comparable option.

SHOEI

• Full-face, sport / sport-touring: RF-1400, RF-SR, X-15 — pure road and track full-face helmets. The X-15 is the race-oriented flagship.
• Full-face touring with sun visor: GT-Air 3, GT-Air II — drop-down sun shield, touring comfort.
• Modular (flip-up): Neotec 3, Neotec II — touring modulars with sun visor.
• Adventure / dual-sport: Hornet X2 — peak visor, on/off-road.
• Open-face / cruiser: J-Cruise II, J·O, RJ Platinum-R — open-face touring and classic styling.
• Motocross / off-road: VFX-EVO — dirt/MX, worn with goggles.

All share SHOEI's intermediate-oval house fit, so a Medium that fits you in an RF-1400 is your starting size in a GT-Air 3 or Neotec 3 — verify on each chart.

HJC

• Full-face, premium sport / race: RPHA 1N, RPHA 12, RPHA 12N (+ Carbon), RPHA 71 (+ Carbon) — the top-tier full-face line.
• Full-face (sport, touring & retro): i71, i70, i10, F70, F71, C10, C70, C71, CS-5, and the retro-styled V10 and V60 — road full-face helmets across price points.
• Modular (flip-up): i100, i91, i90, i80, RPHA 91 (+ Carbon), C91, F100 — flip-up touring.
• Adventure / dual-sport: RPHA 60, DS-X1 — peak visor and face shield, on/off-road.
• Motocross / off-road: CS-MX, CL-X7, i50 — dirt/MX, worn with goggles.
• Open-face / cruiser: V31, i20 / i20N, i30 / i31, C20, IS-Cruiser, IS-33 II, IS-5, RPHA 31 — open-face and retro/cruiser styling.
• Youth: CL-Y, CL-XY, Y10 — smaller-headed and younger riders (measure and use the youth chart).

Same idea within HJC: your HJC size in one model is your starting size in another — but remember a few HJC models shift the L/XL ranges by about a centimeter, so check the specific chart.

Type-specific fit notes

• Modular (Neotec, i100 / i90 / i80, RPHA 91): fit and check the helmet with the chin bar down (riding position). The chin bar should clear your chin and close without contacting your nose.
• Open-face / cruiser (J-Cruise, J·O, V31, i20, IS-Cruiser): you lose the chin-bar reference, so the crown-and-cheek snugness and the roll-off test matter even more.
• Adventure / dual-sport (Hornet X2, DS-X1, RPHA 60): fit as a full-face; if you ride off-road with goggles, check that goggles seat cleanly in the eye port.
• Motocross (VFX-EVO, CS-MX, CL-X7, i50): designed to be worn with goggles — bring or plan for goggles when judging the eye-port and cheek fit.
• Youth (CL-Y, CL-XY, Y10): never size up "to grow into" — a loose helmet can't protect. Measure and fit to the current head.

Still not sure?

If you're between sizes, between shapes, or crossing from one brand to the other, measure carefully in centimeters, start snug, and use the fit check above. If you'd like a hand narrowing it down for your head shape and the bike you ride, reach out to us — we'll help you dial it in.

How we sourced this guide

The fit method and safety guidance here follow primary and manufacturer sources: the U.S. NHTSA helmet-fit guidance, SHOEI's official sizing instructions, and HJC's proper-fit and size-chart pages, cross-checked against Bell and Icon fit references. Size charts and per-model liners can change with model-year updates — always confirm against the current chart on the specific helmet's product page before you buy.