How should a child's riding helmet fit, and can they grow into it?

Troxel's kids' guide warns against buying a bigger helmet because 'they'll grow into it' and says to choose one that fits snugly today. Safety here is the standards bodies' and makers' territory, so we're passing along what they say and not offering a safety verdict of our own.

Trauma Void's guide for kids is a touch more flexible. It says to size up for room to grow only if the helmet still adjusts to your child's current head size, and it adds that you should not compromise sizing or safety. The CDC's Heads Up sheet, written for parents of young riders, says an equestrian helmet should fit snugly all around, with no spaces between the foam or padding and the rider's head. Pony Club's gear sheet puts it bluntly: even a good helmet won't protect a rider's head if it doesn't fit properly, and a bad fit can be dangerous, especially if the helmet slips down and blocks the rider's view.

So where do adjustable helmets fit in? Troxel describes its dial system as helping 'when little heads grow or hair styles change', and the CDC notes that some helmets have removable padding or a fit ring for fine-tuning. That is the middle ground: a helmet that can be tightened to the head in front of you, not one that fits only after a lot of cinching.

Troxel gives that one-inch spot and says a string works too: wrap it, lay it flat and measure it. The CDC puts the tape 'just above' the eyebrows and ears and says to keep it level from front to back.

The CDC also says to bring the rider with you when you shop so you can check the fit, and that sizes vary from brand to brand, so use the brand's own chart. Troxel says its guide covers toddler to youth and sizes by head measurement alone, with no age or weight ranges.

We don't repeat the full measuring walkthrough here. Our Barn Talk on how to measure your head for a riding helmet covers the tape, hat sizes versus centimeters and what to do between sizes.

The CDC sheet is written for parents of children and teens, so we'll lean on it, with Troxel and Pony Club filling in the rest. Do these with the harness buckled and your child wearing the hairstyle they'll ride in.

• Snug, but ask how it feels: no spaces between padding and head, and the CDC adds that a helmet that is too tight can cause headaches. (CDC)
• Level and not too high or low: the front rim about an inch above the eyebrows, the back not touching the top of the neck, the visor parallel to the ground. (CDC, Troxel)
• Vision: you can see your child's eyes, and they can see straight ahead and to each side. (CDC)
• Side straps: a V directly under the ears. (CDC, Troxel)
• Chin strap: centered under the chin and snug, with no more than one or two fingers between chin and strap. (CDC, Troxel)
• The big yawn: ask for a wide-open yawn. The CDC says the helmet should pull down on the head; if it doesn't, the strap needs to be tighter.
• Wiggle test: once fastened, the helmet should not move in any direction, front to back or side to side. Pony Club says the scalp and eyebrows should move with the helmet. If it slides freely, a smaller size is needed; if it squeezes uncomfortably, a larger one. (CDC, Pony Club)
• Condition: the CDC says not to let a rider use a helmet that is cracked, broken or missing padding or parts.

Pony Club's gear sheet says a helmet that squeezes the brow but rocks freely side to side is too round, and one that fits at the sides but rocks front to back is too oval. It says many helmets come with fitting pads that slip inside the hatband to fix this, or a rounder or more oval design may suit better.

On hair, the CDC says to try the helmet on with the style your child will ride in, and that fit can change when the hairstyle does. Pony Club says long hair should be tied back at the nape of the neck, not shoved under the helmet, since that gives a poor fit. A 2009 Utah State University Extension guide says a low ponytail, not a bun or high ponytail. If you have a show braid or bun in mind, try the helmet on that way first.

For the round-versus-oval question in more depth, see our Barn Talk on round or oval head and which helmet shape fits.

Our Helmet Buyer's Guide says never to hand down a used helmet of unknown history, because it may have taken an impact that isn't visible. Troxel says a helmet needs to fit the child wearing it, not a friend, that head shapes differ, and that you can't be sure a used helmet was cared for properly. A 2009 Utah State University Extension guide says equestrian helmets should not be shared among riders.

What do the sources say makes a helmet 'done'? The CDC says to replace any helmet that is damaged or has been in an impact from a fall, because the foam crushes in the impact even when you can't see it, and the foam can't protect against a second one. Troxel says the same about any fall, even if no damage is visible. A used helmet's age matters too, and the Alberta government's Safety Up guide says to check the manufacturer's date on the SEI seal.

For a sibling's helmet where you know every ride it has had, we didn't find guidance from a maker or standards body. If that's your situation, ask the helmet's maker before you pass it along.

Our Helmet Buyer's Guide says a helmet that fit in spring may be too tight by fall. The CDC says a short haircut can change the fit, and Pony Club notes that the headliner can compress over time, making a helmet fit more loosely. Troxel says to replace after any fall, and at least every five years, sooner if the child rides often.

The sources disagree a little on how long a helmet lasts, so the table shows each one. When you can, check your helmet's own instructions, since some makers count from the date of manufacture and others from purchase. We cover it in more depth in our Barn Talk on when to replace your riding helmet.

The CDC says to look for a label with the date of manufacture, which helps if the helmet is recalled, and one that says ASTM, SEI or Snell certified. Pony Club's gear sheet describes the split: ASTM sets the standard, which covers impact absorption and harness design and strength, and SEI checks manufacturers' compliance. SEI says US Equestrian and the US Pony Clubs mandate certification to ASTM standards.

In a 2010 notice, the USEF Dressage Department said that, at its competitions, the rider or a junior's parent, guardian or trainer is responsible for making sure the headgear meets the standard, is properly fitted and is in good condition. It's an old notice, so check the current rule book for your competition. For the standards, how to read a label and what each organization accepts, see our helmet ratings and standards page.

As for 'safest', the CDC says there is no concussion-proof helmet. Virginia Tech's Helmet Lab publishes independent equestrian ratings, saying every helmet it rates has already passed certification and that the ratings are a separate performance assessment. We couldn't confirm whether youth-sized models are in that list, so check the lab's page for the exact helmet. And a bike helmet is not a stand-in: see our Barn Talk on bike helmets for riding.