Every gift guide on this site eventually says the same thing: buy this only if you know their size. This page is how you find out without asking.
There are five measurements. Each one governs a different garment, and none of them is the clothing size the person would tell you. Take these from a jacket in the hall, a boot in the garage and a tape measure, and most of the protective-gear catalogue opens up.
The five measurements
Head circumference — a soft tape about a centimetre above the eyebrows, around the widest part of the back of the skull. This is the only number that sizes a helmet. If you have no tape, a length of string against a ruler works.
Shoe size, and calf circumference — boots need both. Street shoe size gets you to the right neighbourhood; calf circumference is the constraint that decides whether the boot closes, and it is why two people with the same shoe size can need different boots.
Chest — around the fullest part, under the arms, over a t-shirt. Sizes chest protectors and jerseys.
Waist — around the natural waist, not the hips and not where a belt sits. Sizes riding pants. Note that MX pants run small compared with jeans; the pant waist number is rarely the jeans number.
Palm circumference — around the knuckles, excluding the thumb. Sizes gloves.
What each item actually sizes by
| Item | Governed by | Safe to guess? |
|---|---|---|
| Helmet | Head circumference and head shape | No |
| Boots | Shoe size and calf circumference | No |
| Chest protector | Chest | Usually — most are two-band adjustable |
| Riding pants | Waist | Roughly — cut is generous |
| Jersey | Chest | Yes — cut loose over armour |
| Gloves | Palm circumference | Yes, if you size up |
| Goggles | Nothing, for adults | Yes |
| Knee guards | Thigh and calf around the knee | Guards yes, braces no |
| Hydration pack | Nothing — adjustable | Yes |
The two you should not guess
Helmets. Circumference gets you the size; head shape decides whether it is wearable. Brands build around long-oval, intermediate-oval and round-oval shapes, and a helmet that is the right circumference in the wrong shape creates a pressure point that makes it unbearable after twenty minutes. That is a helmet that ends up unworn, which is worse than no gift.
Buy from a retailer with free returns and put the gift receipt in the box even when the measurement is right.
Boots. Fit is model-specific and does not carry across brands. Someone who takes a 10 in one maker may take a 9.5 or an 11 in another, and the calf is a second variable entirely. At $160 to $570 this is the wrong item to be wrong about.
Sizing a child, which follows different rules
Measure, never use the age. Children of the same age differ by a size and a half in both directions, and the age printed on the box is the manufacturer's rough guide rather than a fit statement.
Fit a helmet snug now. A helmet bought to grow into does not protect in the year you bought it — the shell has to hold position on the head in an impact, and a loose one moves before it works.
Check the maximum rider weight before the age rating. On bikes the two frequently disagree, and the weight limit is the one that is a hard engineering constraint rather than a suggestion.
Safe without any measurement at all
If you cannot get a tape near them, everything here still works.
Adult goggle frames are effectively one size. Packs adjust across a wide range. Jerseys are cut over armour. Gloves work if you size up.
Two sizing traps specific to this class
MX pants run small against jeans. A rider who buys 34 jeans is often a 32 or 33 in riding pants, because the pant is cut to sit over a knee brace and under armour rather than on the hip.
"Unisex" means cut for the average man. Most off-road gear in this category is sold as one range, which fits differently on a female rider — usually shorter in the torso and narrower in the shoulder than the size chart assumes. If you are buying for a woman, the fit-sensitive items are worth leaving to her; that is covered in gifts for women who ride.
The bottom line
Five measurements, none of which needs them present: head circumference, shoe size with calf, chest, waist, palm. With the first you can buy a helmet; with the second you still should not buy boots. Everything in the last section needs no measurement at all, which makes it the right place to shop when the tape measure is not an option.
For what to buy at each budget once you have the numbers, start at the 2026 gift guide.
VoltRipper is independent and spec-verified. Always size against the specific brand's own chart — these are the measurements to take, not a substitute for the maker's numbers.
FAQ
How do I size a dirt bike helmet as a gift?
Measure head circumference with a soft tape about a centimetre above the eyebrows and around the widest part of the back of the head, then buy to the brand's own chart for that number. Head shape matters as much as circumference, which is why you should buy from a retailer with free returns and put the receipt in the box even when the measurement is right.
Can I buy dirt bike boots without knowing their size?
No. Boot fit is model-specific and does not carry across brands, and calf circumference is a second constraint that street shoe size tells you nothing about. Boots are the one item on this page where a guess is not worth attempting — buy something else and go shopping together.
What size gloves should I buy?
Measure around the palm at the knuckles, excluding the thumb, and use the brand's chart. If you cannot measure, size up rather than down: a loose glove is uncomfortable and a tight one is unusable. Note that most off-road gloves are sold in men's sizing, so a woman usually takes a size below her usual glove size.
Which gear is safe to buy without any measurement?
Goggles, hydration packs, jerseys, and everything that is not worn — tools, consumables, locks, stands and lights. Adult goggle frames are effectively one size, jerseys are cut loose over armour, and packs adjust across a wide range.