How to Measure Your Head for a Helmet: Step-by-Step Guide

Measuring your head correctly is the first step toward choosing a helmet that fits securely and comfortably. Whether you are buying a bicycle helmet or a motorcycle helmet, guessing your size based on an old helmet, hat size, or general small, medium, and large labels can lead to the wrong fit.

This guide explains how to measure your head for a helmet, how to compare your measurement with a manufacturer size chart, what to do if you fall between two sizes, and how head shape can affect the final fit.

If you have not yet chosen the type of helmet you need, start with our complete helmet buying guide. You can also use our helmet size guide after taking your measurement.

Why You Should Measure Your Head Before Buying a Helmet

Helmet sizing can vary between manufacturers and models. A medium helmet from one company may fit differently from a medium made by another company. For that reason, choosing your usual size without checking the measurement range can cause problems.

An oversized helmet may move too much when worn. A helmet that is too small can create uncomfortable pressure points or may not sit in its intended position.

Measuring your head gives you a clear starting point. You can then compare your result with the size chart for the exact helmet you plan to buy.

What You Need to Measure Your Head

You only need a few simple items:

• A flexible cloth measuring tape
• A mirror
• A pen and paper or your phone to record the measurement
• Someone to help you, if available

A flexible tape is useful because it can follow the shape of your head. If you do not have one, you can use a non-stretch piece of string and measure the string against a ruler afterward.

How to Measure Your Head for a Helmet

Follow these steps carefully:

1. Stand or sit upright in front of a mirror.
2. Place the measuring tape around the widest part of your head.
3. Position the tape slightly above your eyebrows.
4. Run it above your ears.
5. Continue it around the fullest area at the back of your head.
6. Keep the tape level all the way around.
7. Make it snug but not uncomfortably tight.
8. Read the measurement in centimeters.
9. Write the result down.
10. Repeat the measurement to make sure it is accurate.

If your second measurement is different from the first, measure again until you get a consistent result.

Where Should the Measuring Tape Sit?

The tape should go around the widest part of your head rather than around your forehead alone.

A useful starting position is just above your eyebrows. From there, the tape should pass above your ears and around the widest area at the back of your head.

Try to keep the tape horizontal rather than allowing it to rise or fall as it goes around your head.

An uneven tape position can produce a measurement that is smaller or larger than your actual head circumference.

Should the Measuring Tape Be Tight?

The measuring tape should sit snugly against your head without pressing deeply into your skin.

If the tape is too loose, your measurement may be too large. If you pull it very tightly, the result may be smaller than your actual circumference.

The goal is a natural, close measurement that represents the size of your head where the helmet will sit.

Measure Your Head in Centimeters

Helmet size charts commonly use centimeters, so recording your measurement in centimeters can make comparison easier.

For example, instead of relying only on a label such as medium, you can compare your exact circumference with the range listed by the manufacturer.

Do not use one universal helmet sizing chart for every brand. Sizing ranges can differ, so the manufacturer's chart should always be your main reference.

Measure More Than Once

A small measuring error can affect which size you choose, especially if your result sits close to the boundary between two helmet sizes.

Measure your head at least twice. If the results are different, take a third measurement.

If another person is available, asking them to check the tape position can also help because it is easier for someone else to see whether the tape is level around the back of your head.

What Should You Do After Measuring Your Head?

Once you have your head circumference, find the manufacturer's size chart for the exact helmet model you are considering.

Look for your measurement within the listed ranges. Depending on the manufacturer, the chart may show sizes such as:

• Extra Small
• Small
• Medium
• Large
• Extra Large

Do not assume these size labels mean the same thing across all brands.

For more help understanding size ranges, read our complete helmet size guide.

What If Your Head Measurement Falls Between Two Sizes?

Sometimes your measurement will sit close to the limit of two sizes. For example, you may be near the top of one size range and the bottom of another.

There is no single rule that says every rider should automatically choose the smaller or larger size.

Instead, consider:

• The manufacturer's sizing guidance
• The helmet's internal shape
• Your head shape
• The type of helmet
• The adjustment system
• The thickness of the comfort padding

If possible, try both sizes. If you are ordering online, review the size information carefully before completing your purchase.

Head Circumference Is Only Part of Helmet Fit

Your measurement tells you the circumference of your head, but it does not fully describe your head shape.

This matters because two people with the same measurement can find that the same helmet feels completely different.

One rider may feel pressure at the forehead, while another may feel excessive pressure on the sides.

This difference can be caused by the internal shape of the helmet rather than the listed size alone.

Understanding Helmet Head Shapes

Motorcycle helmets are often described using general head-shape categories such as:

• Round oval
• Intermediate oval
• Long oval

These terms describe the general shape of the helmet interior when viewed from above.

An intermediate oval head is generally longer from front to back than side to side. A round oval is closer to an even round shape, while a long oval is more noticeably elongated.

Not every manufacturer uses exactly the same terminology, so use these categories as guidance rather than treating them as universal measurements.

How to Check Your Head Shape

Ask someone to look down at the top of your head or take a photo from above.

Keep your hair as flat as practical so you can see the natural outline of your head.

Do not judge head shape by looking at your face from the front. Helmet head shape refers to the top-down shape of your head.

This check can be especially helpful when choosing a motorcycle helmet.

Measuring for a Motorcycle Helmet

The initial measuring process for a motorcycle helmet is simple: measure your head circumference and compare it with the manufacturer's size chart.

After that, head shape becomes particularly important.

A motorcycle helmet normally fits closely around the head. If the helmet is too large, it may move independently when you turn or shake your head. If the internal shape is wrong, you may notice strong pressure in certain areas.

Read our motorcycle helmet buying guide for additional advice on helmet types, fit, ventilation, visors, and safety labeling.

Measuring for a Bicycle Helmet

The circumference measurement method is similar for a bicycle helmet. Measure around the widest part of your head and compare the result with the manufacturer's chart.

Bicycle helmets commonly use an adjustable internal retention system, often controlled by a dial at the back.

However, this adjustment system should be used to fine-tune the fit within the stated size range. It should not be used to compensate for choosing a helmet that is substantially too large.

For more cycling-specific information, see our bicycle helmet buying guide.

Should You Measure Over Your Hair?

Your hair can affect helmet fit, especially if you regularly wear a thick or bulky hairstyle.

Measure your head in a way that represents how you will normally wear your hair while riding. However, the tape should still follow the actual shape of your head as closely as practical.

Do not buy a much larger helmet simply because your hairstyle changes from time to time.

The helmet still needs to sit and adjust according to the manufacturer's fitting instructions.

Should You Measure Over a Hat or Cap?

In most cases, measure your head directly rather than measuring over a normal hat or cap.

Helmets are generally designed to fit the rider's head using their own padding and retention systems. Adding an ordinary cap underneath can change the fit.

If a manufacturer specifically allows certain thin helmet liners or other accessories, follow those instructions.

How to Measure a Child's Head for a Helmet

Children should also be measured rather than being assigned a helmet size based only on age.

Age does not tell you the exact circumference of a child's head. Two children of the same age can require different helmet sizes.

Use the same general process:

1. Place the tape above the eyebrows.
2. Run it above the ears.
3. Measure around the widest part of the head.
4. Record the result in centimeters.
5. Compare it with the specific manufacturer's size chart.

Choose a helmet that fits the child's current head size. Avoid intentionally buying an oversized helmet only so the child can grow into it.

Common Helmet Measuring Mistakes

Small errors can lead to the wrong size. Try to avoid the following mistakes.

Measuring Too High

If the tape sits only around the upper part of the forehead and misses the widest area at the back, you may get an incorrect measurement.

Measuring Too Low

Running the tape too low around the neck or ears can also give an inaccurate result.

Pulling the Tape Too Tight

The tape should be snug, but it should not compress your skin.

Leaving the Tape Loose

A loose tape may result in choosing a helmet that is larger than necessary.

Using Your Old Helmet Size

Even if you previously wore a medium, a new model may use a different size range.

Using Hat Size Alone

Hat size can provide a rough idea but should not replace a direct head measurement.

How Do You Know If the Measurement Led to the Right Helmet Size?

Your head measurement helps you choose a starting size, but you still need to check the actual helmet after receiving or trying it.

A properly fitted helmet should remain secure when adjusted according to the manufacturer's instructions.

It should not move excessively, fall into your field of vision, or create severe pressure points.

For the next part of the fitting process, read our how should a helmet fit guide.

Signs a Motorcycle Helmet May Be Too Large

After measuring and choosing a size, watch for signs that the motorcycle helmet may be too large:

• It moves independently when you shake your head.
• It rotates easily around your head.
• There are noticeable loose areas around the liner.
• The helmet feels unstable even with the chin strap secured.

Check the manufacturer's fitting instructions before deciding whether you need a different size.

Signs a Motorcycle Helmet May Be Too Small

A motorcycle helmet may be too small or the wrong shape if:

• It cannot sit correctly on your head.
• It produces severe pressure or pain.
• You experience numbness.
• Pressure is concentrated heavily at the forehead or sides.
• You cannot fasten the retention system correctly.

Remember that head-shape mismatch can sometimes feel like a sizing problem.

Signs a Bicycle Helmet May Be the Wrong Size

A bicycle helmet may be too large if it still moves significantly after the retention system is adjusted correctly.

It may be too small if it cannot sit in the intended position or the internal system cannot accommodate your head within the manufacturer's stated size range.

The helmet should sit level and securely rather than being pushed far back or dropping over your eyes.

Do Not Modify a Helmet to Make It Fit

A helmet that does not fit correctly should not be altered by cutting, crushing, removing, or reshaping impact-management material.

You should also avoid adding unapproved material inside the helmet simply to reduce an oversized fit.

If removable or replaceable pads are available, use only components and adjustment methods recommended by the manufacturer.

When a helmet requires major modification to fit, choosing another size or model is usually the better option.

Check Safety Information as Well as Size

Correct sizing is only one part of buying a helmet.

Make sure the helmet is designed for your intended activity and carries the safety information that applies in your market.

For example, bicycle and motorcycle helmets are designed for different uses and can be subject to different requirements.

Our helmet safety standards guide explains CPSC, DOT, ECE, and Snell information in more detail.

Head Measurement Checklist

• Use a flexible measuring tape.
• Measure slightly above your eyebrows.
• Run the tape above your ears.
• Measure around the widest area at the back of your head.
• Keep the tape level.
• Keep it snug without pulling it too tightly.
• Record the measurement in centimeters.
• Repeat the measurement at least once.
• Use the exact manufacturer's size chart.
• Consider head shape as well as circumference.
• Check the actual fit before riding.

Frequently Asked Questions About Measuring Your Head for a Helmet

Where do I measure my head for a helmet?

Measure around the widest part of your head. The tape should generally sit slightly above your eyebrows, pass above your ears, and continue around the fullest area at the back of your head.

Should I measure my head in inches or centimeters?

Centimeters are convenient because many helmet manufacturers list their size ranges in centimeters. Use whichever unit matches the manufacturer's chart, but measure carefully and avoid unnecessary conversions.

How tight should the measuring tape be?

The tape should be snug against your head without pressing deeply into your skin or hanging loosely.

Can I use my hat size to choose a helmet?

Hat size may give you a rough idea, but measuring your actual head circumference and using the manufacturer's helmet chart is more reliable.

What if my measurement falls between two helmet sizes?

Review the manufacturer's recommendations and consider your head shape, helmet type, internal padding, and adjustment range. Try both sizes when possible.

Do motorcycle and bicycle helmets use the same sizing method?

Both generally start with measuring head circumference, but the final fit systems are different. Motorcycle helmets often rely on a close internal fit, while many bicycle helmets use an adjustable internal retention system.

Should I measure my child's head or choose a helmet by age?

Measure the child's actual head circumference. Age alone is not an accurate way to select helmet size.

Final Thoughts on Measuring Your Head for a Helmet

Learning how to measure your head for a helmet takes only a few minutes and can help you avoid many common sizing problems. Use a flexible tape, measure around the widest part of your head, record the result in centimeters, and compare it with the manufacturer's chart for the exact helmet model.

Do not stop at the measurement. Head shape, internal helmet design, retention systems, straps, and actual fit also matter. After choosing a size, make sure the helmet sits securely and does not create severe pressure points.

For the full buying process, return to our helmet buying guide. You can also continue with our helmet size guide, bicycle helmet buying guide, motorcycle helmet buying guide, and helmet safety standards guide. The next step is to read our helmet fit guide and check whether the size you selected actually fits correctly.