How to Measure Head Size for a Helmet: A Simple Step-by-Step Guide

Find your perfect fit using this step-by-step head sizing guide.

Why Measuring Head Size for Helmet Fit Matters

Knowing how to measure head size is the first step to making sure a helmet can do its main job—protecting your head. But it can only work well if it fits just right. A bad fit can make even the best helmet dangerous.

A loose helmet can move around when you crash or even fall off completely. This gives you almost no protection when you really need it. A tight helmet hurts and gives you headaches, which means you won't want to wear it at all.

A good helmet can reduce your risk of head injuries and headaches—but only when it fits right. That’s why knowing how to measure your head for a helmet is essential before buying. This guide will show you exactly how to measure head size for helmet, read sizing charts, and check the final fit.

How to Measure Head Size for a Helmet in 3 Simple Steps

This section gives you the main answer to your question. We've broken down how to measure head size into a simple method that's easy to follow. This measurement is the base of a safe and comfortable fit.

Step 1: Get Your Tools

You need a soft measuring tape, often called a tailor's tape or sewing tape. This tool gives you the best results. If you don't have one, you can use the "string and ruler" method instead. Just find a piece of string that doesn't stretch, a shoelace, or even a phone charging cable. Wrap it around your head like you would a measuring tape, mark where the end meets the string, and then lay it flat to measure with a regular ruler or construction tape measure. A soft tape that bends to your head shape will always give you the best result.

Step 2: Put the Tape in the Right Place

Getting the right spot is key when learning how to measure for a helmet properly. You need to measure the widest part of your head so the helmet can fit over it. Wrap the measuring tape around your head about one inch above your eyebrows and ears. The tape should go around the biggest point on the back of your head. Look in a mirror to make sure the tape is level all the way around and not tilted. It should be snug against your head but not tight enough to make marks on your skin.

Step 3: Read and Write Down Your Number

Look at the number where the end of the tape meets the rest of the tape. This is your head size around. We suggest doing this three times and using the biggest of the three numbers. This helps make up for small differences in where you put the tape. Write down this number in both centimeters and inches. Different ebike helmet brands use different units on their sizing charts, so having both will make the next step easier.

Use this simple calculator to match your head circumference with standard helmet sizing. It’s a fast way to check what size you fall into based on your measurement, especially helpful when comparing bike helmet sizes across brands.

Helmet Sizing Charts Explained

Once you have your measurement, you need to turn that number into a helmet size like Small, Medium, or Large. This is where you must pay close attention to the specific brand and model you want to buy.

Every helmet brand has its own sizing chart. There's no standard rule, which means a "Medium" from one company could fit very differently from a "Medium" from another. The main rule of helmet buying is to always check the specific sizing chart for the exact helmet model you want.

You can usually find this on the product page online or on the helmet's box.

Here's an example of what a sizing chart looks like. Don't use this chart to buy a helmet; it's just for showing you how it works.

Every helmet brand has its own helmet sizing chart, which is why measuring first is critical. If you’re shopping for multiple activities, like cycling or skateboarding, comparing bike helmet sizing across manufacturers is a must.

A common question is what to do if your measurement falls between two sizes. For example, if your head is 59.5 cm, you might be between a Medium and a Large. Usually, you should pick the smaller size.

The helmet's inside padding will press down and shape to your head a little with use, making a better fit over time. But this advice also depends on your head shape.

Why Head Shape Affects Helmet Sizing

While the distance around your head is the main number, it only tells part of the story. Our heads aren't perfectly round, and head shape is important for getting a truly comfortable and safe fit. This is especially true for harder helmets used for things like riding motorcycles, snowboarding, or horse riding.

When your head shape doesn't match the helmet's inside shape, you get "hot spots" or painful pressure points.

There are three common head shapes:

• Long Oval: The head is much longer from front to back than it is from side to side. People with this shape often feel uncomfortable pressure on their forehead when wearing a regular helmet.

• Middle Oval: This is the most common head shape, where the head is a little longer from front to back than it is from side to side. Most helmets are made with this shape in mind.

• Round Oval: The head's length from front to back and its width from side to side are almost the same. People with this shape often feel pressure on the sides of their head.

Learning how to measure head size correctly not only helps you find the right size, but also ensures better compatibility with your head shape. This simple step can make a big difference in comfort and safety when choosing any helmet. You can also put a mirror on a flat surface below you and look down into it.

This will give you a clear visual clue. Some expensive helmet makers, especially in racing, will say which head shape their different models are made for. Look for this information in product descriptions and reviews.

As noted in the Snell Memorial Foundation's fitting advice, getting even contact between your head and the helmet liner is important for maximum safety, and this relates directly to matching your head shape correctly.

The 5-Test Fit Check for Helmet Sizing Accuracy

Measuring your head is step one, but the final check happens when you try the helmet on. Whether you're in a store or just got your online order, doing this series of checks is a must. A correct fit should feel snug, firm, and put even pressure all around your head, like a firm, comforting hug.

It should not be painful, pinching pressure at any single point. Here's a five-step list to check a perfect fit:

1. The First Feel: The helmet should slide onto your head snugly, needing a little effort. If it drops into place with no resistance at all, it's almost certainly too big. If you have to force it on painfully, it's too small.

2. The Eyebrow Test: With the helmet on, it should sit level on your head. The front edge should rest about one to two finger-widths above your eyebrows. This spot ensures proper forehead protection without blocking your vision.Now, try to move the helmet with your hands. A well-fitting helmet will grip your scalp, and you should see your eyebrows and the skin on your forehead move with it.

3. The Pressure Point Check: This is an important test for comfort. Put on the helmet and wear it for 10 to 15 minutes. This gives your head time to settle in and show any problems.After taking it off, look in a mirror and check your skin for any bright red, sore spots. These "hot spots" show too much pressure and a bad fit, likely because of a shape mismatch. These spots will only become more painful on long range ebike rides or outings.

4. The Shake Test: Before fastening the chin strap, do the shake test. Lean forward and shake your head gently from side to side, and then nod it forward and backward. The helmet must stay securely in place.If it shifts a lot, feels like it might fall off, or actually does fall off, it's too big.

5. The Chin Strap Test: Finally, fasten the chin strap. It should be snug enough against your chin that you can only fit one or two fingers between the strap and your skin. It should not feel like it's choking you or making it hard to breathe or swallow.Check the "Y" junction of the side straps; they should meet at a point just below your earlobes for a secure and comfortable fit.

Avoid These Common Head Size Measurement Mistakes

To make sure you get it right the first time, avoid these common mistakes when figuring out your helmet size.

• Guessing Your Size: Never assume your size or rely on the size of an old helmet. Your head size can change, and as we've covered, sizing isn't the same between brands. Always measure again.

• Measuring in the Wrong Spot: The most common error is measuring too high or too low on the head. Remember the rule: measure the widest distance around, about one inch above your eyebrows and ears.

• Forgetting About Head Shape: A helmet with the right distance around can still be a poor fit if it doesn't match your head shape. Remember to think about if you are a long oval, round oval, or middle oval.

• Ignoring the Brand's Size Chart: A medium is not always a medium. Always find and use the specific sizing chart for the exact helmet model you are buying.

• Settling for "Good Enough": A helmet fit is a matter of safety. A "pretty good" or "almost right" fit is not okay. It must be perfectly snug and comfortable.

Your Safety is Non-Negotiable

To wrap up, a correctly fitting helmet is the single most important piece of safety gear you can own for your chosen activity. Taking a few minutes to learn how to measure head size for helmet is a simple skill that pays huge benefits.

It makes sure your helmet is not only comfortable enough to wear every time but also that it can give maximum protection if you have an accident. Now that you have the knowledge, you can measure with confidence, buy the right size, and ride safely.

This helps make sure the helmet sits level and doesn’t create pressure points. While how to measure head size gives you a number, matching that number to the right helmet sizing category—especially for long or round heads—makes a big difference in fit and comfort. Ready to find your perfect helmet? Use our size calculator above and check out our best-fit models here.

FAQs

1. How do I measure my head size for a helmet?
To measure your head size, wrap a flexible tape measure around the widest part of your head—typically just above your eyebrows and ears. Keep the tape level and snug, but not tight. Note the circumference in centimeters or inches and use it to check the helmet brand’s size chart. Most adult head sizes range between 52–62 cm.

2. What is the correct position to place the measuring tape?
The measuring tape should sit approximately 1 inch (2.5 cm) above your eyebrows, following a straight line around the widest part of the back of your head. This position aligns with how a helmet sits when worn correctly. Measuring too high or low may result in an incorrect helmet fit.

3. What size helmet do I need for a 22 inch (56 cm) head?
A 22 inch (56 cm) head typically falls into a Medium (M) size in most helmet sizing charts. However, sizing can vary between brands. Always cross-check with the specific brand’s size guide. For example, one brand’s Medium may range from 55–58 cm, while another may consider 56 cm as a Small–Medium.

4. How does bike helmet sizing differ from other helmets?
Bike helmets prioritize ventilation, weight, and aerodynamic shape. While sizing principles (measured by head circumference) are similar to motorcycle or snow helmets, bike helmets often come with adjustable fit systems—like dial adjusters or pads—for fine-tuning. Always measure your head first; don't assume sizes will match across different helmet types.

5. What is the 2-2-2 rule for fitting a helmet?
The 2-2-2 rule is a quick check for proper bike helmet fit:

• 2 fingers between your eyebrows and the helmet front
• 2 fingers form a V-shape under your ears using the straps
• 2 fingers fit between your chin and the chin strap

This ensures your helmet sits correctly, stays secure, and offers optimal protection.