Caleb MorganBy Caleb Morgan

Updated November 2026

The giro scamp mips youth bike helmet size chart tells you which size to order based on your child’s head circumference, and that single measurement is the most reliable way to choose. In this guide, you will measure your child’s head correctly, match the number to the right Scamp MIPS size, and run a quick fit check so the helmet sits level, snug, and stays put in a crash.

Why the Giro Scamp MIPS Size Chart Matters

Youth helmets look similar across sizes, but the internal padding and shell curvature are built around a specific head range. A helmet that is one size too large can rock forward or slide back, exposing the forehead. A helmet that is too small will sit high on the head and pinch. Either problem reduces protection and makes kids less likely to keep wearing it.

Giro sizes its youth helmets by head circumference, not by age. Children grow quickly, and two kids of the same age can differ by an inch or more in head size. For that reason, age is only a rough starting point. Always measure.

What You Need Before You Measure

  • A flexible cloth or vinyl measuring tape (a sewing tape works well)
  • A pen or marker to note the number
  • Your child, sitting relaxed and not wearing a hat or hair accessories
  • The Giro size chart from the manufacturer’s current specifications

Step-by-Step: Measure Your Child’s Head

  1. Position the tape. Wrap the tape around the head about one inch above the eyebrows and above the ears. This is the line where a helmet would sit.
  2. Keep it level. The tape should run straight around the back of the head at the same height all the way around. If it tilts up at the back, lower the front and re-check.
  3. Snug, not tight. The tape should touch the head without compressing the hair or skin. Hold the tape flat against the head.
  4. Read and record the number. Read the measurement in inches and in centimeters if the chart lists both. Note the value to the nearest half inch.
  5. Measure twice. Repeat the measurement and confirm the number. If the two readings differ by more than a quarter inch, measure again.

How to Read the Size Chart

Once you have the head circumference, find the matching row on the Giro size chart. Youth helmet charts are typically organized in ranges, so a child whose measurement falls near a boundary may need to decide between two sizes. In that case, the fit check below is the tiebreaker.

Step What to Check Good Result
Circumference Measured head size against chart range Falls inside the listed range
Boundary cases Measurement sits at the edge of two sizes Try the smaller size first if it fits snugly
Fit adjustment Dial or pad system tightened Helmet stays in place with minimal movement
Chin strap Strap adjusted and buckled Two fingers fit between strap and chin

Checking the Fit on Your Child

A chart gets you close, but the fit check confirms the choice. Put the helmet on your child’s head with the dial or internal fit system set to its snuggest position, then work through these checks.

Position on the Head

The front edge should sit about one finger-width above the eyebrows. If it sits lower, the helmet is too far forward and may limit vision. If it sits high, exposing the forehead, the helmet is too far back.

Side Straps

Adjust the side straps so they form a V shape just below the ears. The buckle should sit directly below the ear lobe, under the jaw hinge. Straps that rest on the ear or sit too far forward need adjusting.

Chin Strap

Buckle the chin strap and tighten until you can fit no more than one or two fingers between the strap and the chin. Have your child open the mouth wide, like a yawn. The helmet should press down on the head, not tilt back.

Movement Test

With the helmet fastened, hold the rim and try to rotate it forward and back, then side to side. The helmet should move only slightly with the scalp. If it shifts independently of the head, tighten the fit system or consider the next size down.

Common Mistakes

  • Buying a size up to grow into. A loose helmet offers less protection right away, so buy for the head your child has today.
  • Measuring over hair or a hat. Bulky hair or a beanie inflates the number and can lead to choosing too large a size.
  • Relying only on age. Two children of the same age can need different sizes.
  • Skipping the chin strap check. A loose strap lets the helmet move in a crash.
  • Ignoring wear over time. A helmet that has been in a crash or has visible damage should be replaced, following the manufacturer’s guidance.

Tips for Getting the Best Fit

  • Measure in the same conditions each time, ideally on a day when your child has not just washed or styled their hair.
  • If a child is between sizes, try both on in person when possible and choose the one that passes the movement test.
  • Re-measure at the start of each riding season, since children can grow several sizes in a year.
  • Let your child wear the helmet around the house for a few minutes to see if pressure points develop.
  • Teach your child to adjust the chin strap and dial before every ride. Good habits matter as much as good sizing.

A few simple items make sizing and fit checks easier and more accurate:

  • Flexible sewing tape measure – A soft tape conforms to the head better than a rigid ruler, giving a more accurate circumference reading. View on Amazon
  • Giro Scamp MIPS youth bike helmet – The helmet itself, ordered in the size your measurement points to, is the item you need to match against the chart. View on Amazon
  • Replacement helmet pads – Fit pads can fine-tune comfort when a child falls between sizes, though they should not be used to compensate for a helmet that is clearly the wrong size. View on Amazon

If you are comparing helmets from other brands, the Bike Helmet Sizes Chart: How to Find Your Right Fit in 5 Steps guide covers general sizing principles that apply across manufacturers. For a broader look at youth options, see 7 Best Youth Dirt Bike Helmet Size Chart Picks for Young Riders (2026). Riders who ride off-road may also find Dirt Bike Helmet Size Chart: 10 Best Helmets Compared in 2026 useful when comparing shell styles and fit systems.

FAQ

How do I know if my child needs a youth or adult Giro helmet?

Measure head circumference and compare it to both charts. Youth helmets cover smaller head sizes, and the adult range begins at a larger circumference. If the measurement falls in the youth range, choose a youth size.

Should I measure in inches or centimeters?

Either works, as long as you match the unit to the chart. Many charts list both. Use the unit the chart specifies so you compare the same numbers.

My child is between two sizes. Which should I choose?

Try the smaller size first. If it fits snugly without pressure points and passes the movement test, it is usually the better choice. A helmet that is too large is the bigger safety concern.

How long should a youth helmet fit?

Fit depends on how quickly your child grows. Re-measure at the start of each season and check fit regularly, since children can outgrow a helmet within a year.

Can I use fit pads to make a bigger helmet fit?

Fit pads can improve comfort and fine-tune the fit within a size, but they cannot correct a helmet that is clearly too large. If the helmet rocks or slides after adding pads, choose the next size down.

Does the MIPS feature change how I size the helmet?

No. MIPS is a low-friction liner designed to reduce rotational motion in certain impacts. Sizing is still based on head circumference and the fit checks described above.

When should a helmet be replaced?

Replace a helmet after a crash, if it shows visible damage, or if the manufacturer specifies a service life. Follow the guidance in the Giro owner materials for your specific model.

Should I ask a professional about helmet fit?

If your child has a head shape that makes fitting difficult, or if you are unsure after measuring and checking, a bike shop or a qualified fitter can help. For any concerns about a head injury, consult a medical professional.

Conclusion

Measure your child’s head circumference carefully, match it to the Giro size chart, and confirm the choice with a fit check. A helmet that sits level, stays snug, and passes the movement test will protect your child far better than one chosen by age alone. Re-measure each season and replace the helmet after any crash.

Ready to choose one?

Caleb Morgan

About Caleb Morgan

Caleb Morgan is part of our editorial team and reviews and edits our cycling for beginners guides, checking product details against manufacturer specifications and owner feedback.