Motorcycle Helmet Size Guide: How to Get the Right Fit

Part of our Motorcycle Helmet Buying Guide: How to Choose the Right Helmet

Finding the right motorcycle helmet size is about more than choosing small, medium or large. A helmet needs to sit securely on your head, fit comfortably around your cheeks and forehead, and remain properly positioned while you're riding.

Get the fit wrong and even an expensive helmet can be uncomfortable or may not provide the protection it's designed to offer.

Whether you're buying your first helmet for Initial Basic Training (IBT), replacing an older model or trying a different brand, this guide explains how to measure your head, check the fit and recognise common sizing problems.

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How to measure your head for a motorcycle helmet

Your head circumference is the starting point for finding the correct helmet size.

You'll need a flexible measuring tape, ideally marked in centimetres, and a mirror or somebody to help you.

Step 1: Position the measuring tape

Wrap the tape around your head, approximately 1 to 2 cm above your eyebrows.

It should pass above your ears and around the widest part of the back of your head.

Keep the tape level and make sure it sits comfortably against your head without pulling it excessively tight.

Step 2: Take your measurement

Read the measurement in centimetres.

For example, you might measure 57.5 cm. Record the actual measurement rather than immediately rounding it to the nearest helmet size.

Measure again to make sure you've taken it consistently.

If the measurements differ, check the tape position and repeat.

Step 3: Check the helmet manufacturer's size chart

Use your head circumference to check the sizing chart for the specific helmet model you're considering.

Different manufacturers use different sizing ranges, and there can be differences between models from the same brand.

A medium in one helmet may not fit like a medium in another.

Always refer to the appropriate manufacturer's sizing guidance rather than assuming that sizes from different brands are interchangeable.

Step 4: Confirm the fit

Your measurement helps you select a size to try, but it cannot tell you whether the helmet's internal shape suits your head.

The final decision should be based on how securely and comfortably the helmet fits.

Important: If your measurement falls between two listed sizes, don't automatically choose the larger or smaller one. Use the manufacturer's guidance and assess the fit carefully.

Motorcycle helmet size charts: why there isn't one universal chart

You may have seen generic motorcycle helmet size charts online showing measurements for XS, S, M, L and XL.

They can be useful for understanding how helmet sizes work, but they should not replace model-specific sizing information.

Two helmets with the same size label may differ in their internal shape, padding, shell sizing and fit.

For example, somebody whose head measures 58 cm might fit one model comfortably but experience pressure points in another model carrying the same nominal size.

This doesn't necessarily mean either helmet is incorrectly sized. The internal shapes may simply be different.

Our advice: Treat your head circumference as a starting measurement, then use the specific manufacturer's size chart and fitting instructions.

How should a motorcycle helmet fit?

A correctly fitting motorcycle helmet should feel snug, stable and secure without causing pain.

It should make consistent contact around your head, with no large gaps or obvious areas of excessive pressure.

A new full-face helmet will generally feel firmer than an old helmet that you've worn for several years.

This is normal, as the comfort padding can compress through regular use.

However, snug and painful are not the same thing.

How tight should the cheek pads be?

On a full-face helmet, the cheek pads should sit firmly against your cheeks.

They may push your cheeks in slightly, particularly when the helmet is new.

If you speak or chew, you may notice your cheeks moving against your teeth.

This can be normal, provided it isn't painful.

What you don't want is a helmet that feels loose around the cheeks or moves freely when you turn your head.

Equally, excessive pressure that causes significant discomfort is a sign that the fit needs attention.

Some helmet models offer alternative cheek-pad thicknesses. Only use compatible padding approved by the manufacturer.

How should the forehead feel?

The helmet should sit comfortably across your forehead without creating one concentrated pressure point.

If you feel a painful spot in the centre of your forehead, particularly after several minutes, the helmet may not suit your head shape.

Simply going up a size might remove the immediate pressure, but it could also make the helmet too loose elsewhere.

A different helmet model may be the better solution.

How should the helmet fit around your ears?

Your ears should sit comfortably inside the helmet without being folded or trapped awkwardly.

Some helmets require you to adjust your ears slightly after putting them on.

Once positioned, there shouldn't be painful pressure or persistent discomfort.

If the helmet presses against your ears, check that you're putting it on correctly and that the internal padding is properly positioned.

Five checks to make when trying on a motorcycle helmet

Once you've selected a helmet using your head measurement, perform these checks before deciding whether it fits.

1. Check how it sits on your head

The helmet should sit in its intended position, generally with the brow area just above your eyebrows.

It shouldn't sit unusually high or tilt backwards.

Make sure you have a clear field of vision and that the helmet isn't obstructing your eyes.

2. Check for sideways movement

With the helmet on, gently hold it and try to move it from side to side.

Your scalp and cheeks should move with the helmet rather than allowing it to rotate freely around your head.

A helmet that moves easily may be too large or the wrong internal shape.

3. Check forwards and backwards movement

Gently move the helmet forwards and backwards.

It should remain securely positioned rather than sliding excessively across your forehead or lifting away from the back of your head.

4. Fasten the chin strap

Always assess the fit with the chin strap correctly fastened.

Check that the fastening system works properly and that the strap is adjusted in accordance with the manufacturer's instructions.

A helmet may feel secure when you're standing still but behave differently if the strap is loose.

A properly fastened helmet should resist rolling or lifting off your head. Follow the manufacturer's retention and roll-off checks.

5. Wear it for 15 minutes

A helmet can feel comfortable when you first put it on but develop pressure points after a few minutes.

Keep it on for approximately 15 minutes while sitting or standing normally.

Notice whether discomfort develops around your forehead, temples, crown, cheeks or ears.

This is one of the simplest ways to identify a helmet that isn't quite right.

Motorcycle helmet head shapes explained

Your head circumference isn't the only thing that determines which helmet will fit.

The shape of your head matters too.

Helmet manufacturers use different internal profiles, often described in terms of round, intermediate oval and long oval shapes.

These descriptions refer to the general proportions of the helmet's internal fit.

Round oval

A round oval shape is relatively broad from side to side compared with its front-to-back length.

Some riders with this head shape may experience pressure at the forehead when wearing helmets designed for more elongated heads.

Intermediate oval

An intermediate oval shape is somewhat longer from front to back than from side to side.

Many road helmet designs use variations of this general shape, although the precise fit differs between models.

Long oval

A long oval head shape has a noticeably greater front-to-back proportion.

Riders with this shape may find some helmets press uncomfortably against their forehead or the back of their head.

How do you know your head shape?

You can get a rough idea by looking at the outline of your head from above, with help from another person.

However, you don't need to classify your head shape perfectly to find a good helmet.

The more reliable approach is to try helmets and pay attention to where pressure develops.

If the circumference is correct but a helmet causes painful pressure in one area, try a different internal shape rather than automatically moving up a size.

How to tell if a motorcycle helmet is too big

An oversized helmet may initially feel comfortable because there's little pressure around your head.

But comfort caused by excessive looseness isn't a good fit.

Common signs include:

  • The helmet moves independently of your head.
  • It rotates easily when you turn it from side to side.
  • The cheek pads barely touch your cheeks.
  • It moves excessively forwards or backwards.
  • It can be rolled or lifted excessively despite the chin strap being correctly fastened.
  • It feels unstable when you move your head.

A helmet shouldn't be able to wobble around your head.

If it does, check the size and shape before using it.

Don't rely on tightening the chin strap to compensate for a helmet that's too large.

How to tell if a motorcycle helmet is too small

A helmet that's too small can also cause problems.

Some pressure is normal, especially with a new helmet, but significant discomfort isn't.

Signs that a helmet may be too small or the wrong shape include:

  • Painful pressure across your forehead.
  • Persistent discomfort around your temples.
  • Numbness or headaches during fitting.
  • Excessive pressure around your ears.
  • Difficulty positioning the helmet correctly.
  • Pressure that becomes increasingly uncomfortable after a few minutes.

If the helmet feels painfully tight, remove it.

Don't assume the padding will eventually compress enough to resolve serious discomfort.

Sometimes a different size is required. In other cases, the problem is the helmet's shape.

Should you buy a tighter motorcycle helmet because the padding will loosen?

It's true that some of the comfort padding inside a motorcycle helmet can settle over time.

However, that doesn't mean you should deliberately buy a helmet that's too small.

A correctly fitted new helmet should feel snug but wearable.

It shouldn't cause significant pain or leave you feeling that you need to endure several uncomfortable rides before it becomes usable.

Equally, you shouldn't buy a loose helmet expecting it to somehow become more secure.

The goal is to get the fit right from the beginning.

Motorcycle helmet fitting if you wear glasses

If you wear prescription glasses or sunglasses while riding, you need to check the helmet fit with them in place.

A helmet may feel perfectly comfortable without glasses but press against your temples once the frames are fitted.

When trying on a helmet:

  1. Put the helmet on and fasten it correctly.
  2. Carefully position your glasses as you normally wear them.
  3. Check that the arms aren't pressing painfully into your temples.
  4. Make sure the glasses sit in their normal position.
  5. Check that you can remove them without excessive difficulty.
  6. Wear the combination for several minutes.

Some helmets incorporate channels designed to accommodate spectacle arms.

These can be useful, but don't assume a particular model has them without checking its specifications.

If your glasses cause pressure, consider another helmet model or frame design rather than choosing an oversized helmet.

Does helmet fit differ between full-face and modular helmets?

The basic fitting principles remain the same.

A helmet must fit securely around your head and remain properly positioned when fastened.

However, full-face and modular helmets can feel different because of their chin-bar construction and internal design.

When trying a modular helmet, check the fit with the chin bar fully closed and locked.

Open and close it according to the manufacturer's instructions to confirm that you can operate it comfortably.

The movable chin bar doesn't compensate for an incorrectly fitting helmet.

If you're comparing the two designs, read our Motorcycle Helmet Buying Guide for a broader explanation of helmet types.

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How should a motorcycle helmet fit a child?

Children's motorcycle helmets require the same careful attention to correct sizing and secure fit as adult helmets.

Never purchase an oversized helmet expecting a child to grow into it.

An incorrectly fitting helmet may not remain in position as intended.

Measure the child's head, check the manufacturer's dedicated youth sizing guidance and assess the helmet's fit carefully.

The helmet should be appropriately approved for the intended use and should remain securely positioned with the retention system correctly fastened.

A responsible adult should assist with selection and fitting.

Do not assume that an adult extra-small helmet is equivalent to a youth helmet.

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Can you adjust the fit of a motorcycle helmet?

Some helmet models allow limited fit adjustments through manufacturer-approved replacement cheek pads, crown pads or other compatible comfort components.

This can be useful when the overall helmet size is correct but a small fit adjustment is needed.

However, not every helmet supports interchangeable internal padding.

Never cut, compress, remove or modify the impact-absorbing liner to change how a helmet fits.

Do not substitute unapproved padding or make structural alterations.

If a helmet is fundamentally the wrong shape or size, changing the model is usually more appropriate than trying to force it to fit.

How to check the fit when buying a motorcycle helmet online

Buying online makes it particularly important to measure correctly and check the product information.

Before ordering:

  1. Measure your head circumference in centimetres.
  2. Find the manufacturer's size chart for the exact helmet model.
  3. Check whether your measurement sits near a size boundary.
  4. Read the helmet's specifications and any relevant fitting guidance.
  5. Review the retailer's return conditions.
  6. Contact the retailer if you're uncertain about sizing.

When the helmet arrives, inspect it and try it on indoors.

Check the crown fit, cheek pads, pressure points, chin strap and overall stability.

Keep the helmet on for several minutes so that any discomfort becomes apparent.

Avoid removing labels, protective coverings or packaging until you've confirmed the fit and checked the applicable return conditions.

Don't ride in a helmet that doesn't fit correctly.

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Frequently asked questions

How do I know what size motorcycle helmet I need?

Measure your head circumference just above the eyebrows and around the widest part of the back of your head. Compare the measurement with the specific helmet manufacturer's size chart, then confirm the fit.

Should a motorcycle helmet squeeze your cheeks?

Full-face motorcycle helmets should generally fit firmly against your cheeks. Some cheek compression is normal, but the pressure shouldn't be painful or cause significant discomfort.

Is a motorcycle helmet supposed to feel tight at first?

A new helmet should feel snug and secure. It shouldn't feel loose, but it also shouldn't cause painful pressure points, headaches or numbness.

Is a 58 cm head a medium or large motorcycle helmet?

It depends on the manufacturer and model. A 58 cm measurement can fall into different labelled size ranges. Always use the specific helmet's size chart rather than relying on a universal conversion.

Do motorcycle helmets stretch over time?

The rigid protective structure isn't intended to stretch to fit your head. Comfort padding may compress with regular use, which can make a helmet feel less snug over time.

What if I'm between motorcycle helmet sizes?

Check the manufacturer's guidance and try the relevant sizes. The correct choice depends on the helmet's internal shape and actual fit, not simply whether you prefer a looser or tighter feeling.

Can I wear glasses with a motorcycle helmet?

Yes. Try the helmet with your glasses in place to make sure the frames fit comfortably without creating pressure around your temples.

Should I buy a motorcycle helmet one size bigger?

Not simply for comfort. An oversized helmet can move excessively and may not remain securely positioned. Choose the size that fits correctly according to the manufacturer's instructions.

How long should I wear a helmet when trying it on?

Wearing it for approximately 15 minutes is a useful practical check for developing pressure points. It doesn't replace the manufacturer's recommended fitting and retention checks.

Do HJC and MT motorcycle helmets fit the same?

You shouldn't assume they do. Sizes and internal shapes can vary between manufacturers and individual models. Check the appropriate size chart for the helmet you're considering.

Find your size, then find your helmet

Getting the right motorcycle helmet size is worth taking seriously.

Start by measuring your head, use the manufacturer's sizing guidance and make sure the helmet fits securely without causing painful pressure.

If a helmet doesn't feel right, try another size or model rather than accepting an uncomfortable or loose fit.

At Franklin Motors, you can explore helmets for commuting, touring, sports riding, adventure riding and more.

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For help with helmet sizing, contact Franklin Motors on 01 538 5005.

You can also read our Complete Motorcycle Helmet Buying Guide for advice on helmet types, safety standards, features and choosing the right helmet for your riding.

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