Cosplay helmets and wearable armor only work if they fit. We size every wearable piece in our shop from XXS to XXXL, which sounds straightforward but actually covers a lot of physical variation. Here's exactly what each size means, how to measure correctly, and what to do if you fall between sizes.
The Full Size Range — Helmets
Our wearable helmets are sized by head circumference, measured around the widest part of your head (above the ears, across the forehead, around the back). Here's the chart:
| Size | Head Circumference | Hat Size Equivalent |
|---|---|---|
| XXS | 52-53 cm (20.5-20.9 in) | 6 1/2 |
| XS | 54-55 cm (21.3-21.7 in) | 6 3/4 |
| S | 55-56 cm (21.7-22.0 in) | 6 7/8 |
| M | 57-58 cm (22.4-22.8 in) | 7 1/8 |
| L | 59-60 cm (23.2-23.6 in) | 7 3/8 |
| XL | 61-62 cm (24.0-24.4 in) | 7 5/8 |
| XXL | 63-64 cm (24.8-25.2 in) | 7 7/8 |
| XXXL | 65+ cm (25.6+ in) | 8+ |
This range covers virtually every adult head size. If you fall outside XXXL, we can do custom sizing — just mention it when you order.
How to Measure Your Head Correctly
This is the step where most cosplayers get into trouble. Bad measurements lead to ill-fitting helmets, and we can't resize a printed helmet after the fact. Take an extra five minutes here.
The Right Tool
Use a flexible soft tape measure — the kind tailors use. If you don't have one, a piece of string and a ruler works too. Don't use a hard metal tape measure; you can't get an accurate read.
The Right Position
- Stand in front of a mirror
- Position the tape so it goes around your head at the widest point — just above your eyebrows in the front, around the back where your skull is widest (this is usually about 1.5 cm above your hairline at the back)
- The tape should be level all the way around. Not angled up at the back or down at the front
- Snug but not tight. The tape should rest on your skin without compressing it
- Read the measurement at the point where the tape crosses itself
Get someone else to do this for you if possible. Self-measuring your own head circumference is famously inaccurate.
For a deeper walk-through of head measurement, see our complete head measurement guide.
If You're Between Sizes
If your measurement falls between two sizes (say, 56.5 cm — right between S and M), here's our recommendation:
Always go up.
Here's why: you can pad a slightly large helmet with foam inside to make it fit perfectly. You can't make a tight helmet bigger. A helmet that's slightly too small will press uncomfortably on your forehead, your ears, and the top of your head — by hour three of a convention, you'll be miserable. A helmet that's slightly too large, padded properly, fits perfectly all day.
Standard foam padding (the same kind used in bike helmets) is cheap and easy to find. We can include extra padding with your order if you want — just ask.
The Full Size Range — Armor
For wearable armor (chest plates, full suits, gauntlets), we don't use the XXS-XXXL system the same way. Armor is sized to your specific body measurements. When you order a wearable armor piece, we'll send you a measurement guide that asks for:
- Chest circumference (around the fullest part of your chest, under the armpits)
- Shoulder width (across the back, from shoulder point to shoulder point)
- Torso length (from the base of your neck to the top of your hip)
- Waist circumference (around your natural waist, just above the belly button)
- Bicep circumference (largest part of your upper arm, flexed)
- Forearm circumference (largest part of your forearm)
- Thigh circumference (top of the thigh, where it meets the hip)
- Calf circumference (largest part of your calf)
Not every armor piece needs all of these. A chest plate alone needs chest, shoulders, torso length, and waist. Full body armor needs everything.
Why Custom Body Measurements Matter for Armor
3D printed armor doesn't stretch. Once it's printed, the dimensions are fixed. If we use generic "medium" or "large" measurements, the armor will fit only the generic medium or large body — which doesn't exist in reality. Real bodies have unique proportions: long torso with short arms, broad shoulders with narrow waist, etc. Custom-fit armor accounts for your specific shape.
This is the main difference between buying a $100 generic Halo helmet on Amazon and ordering a sized piece from us. Generic costs less. Custom-fit feels like it was made for your body — because it was.
Wearable Gauntlets
The Wearable Malenia's Prosthetic Arm and Wraithguard Gauntlet are sized to your forearm and bicep measurements. The forearm circumference (largest part) and your arm length from elbow to wrist are the key measurements.
These are more forgiving than helmets — you can adjust the inner padding to make a slightly large gauntlet fit, and foam padding compensates for small variations.
Common Sizing Mistakes
The four most common mistakes we see:
- Measuring over hair — if you have a lot of hair, measure with the hair down and unstyled, the way it will be under the helmet. Don't measure with a bun or ponytail in
- Measuring with the tape too high — the tape should sit on your skin, not float above your head. If it's loose, the measurement reads bigger than your actual head
- Self-measuring without a mirror — you can't see whether the tape is level. Get help or use a mirror
- Trusting old hat size estimates — don't assume "I wear a size 7 hat so I'm a medium." Always re-measure for cosplay helmets specifically
The Comfort Layer
Every helmet comes with internal foam padding. This handles minor sweating, friction, and small fit variations. For long conventions (8+ hours wearing), you may want to add a moisture-wicking liner underneath the foam — a simple cotton skullcap or a balaclava-style liner works.
For more on comfort during long convention days, see our surviving Texas conventions guide.
If You're Ordering for Someone Else
Gift orders for cosplay helmets are tricky because you can't measure the recipient's head without giving away the surprise. Two strategies:
- Have them "casually" try on hats with you — a hat that fits them snugly gives you their size
- Order with a return-friendly conversation in advance — we can ship to you, you confirm the fit, then it goes to the recipient. Or we can hold the order until you confirm size
Talk to us at info@lonestarcosplay.com if you're planning a gift order. We'll work with you.
One Final Thought
The measurement step is the difference between a cosplay you love wearing and one that hurts after 30 minutes. Spend the five minutes. Get help. Measure twice. The fit is worth it.
