Sitka vs KUIU vs First Lite: How Sizing Actually Compares

If you're buying used hunting apparel online, sizing is the single biggest reason gear gets returned. And when you're shopping across brands — Sitka, KUIU, and First Lite — the problem gets worse, because none of them size the same way. A large in one brand is not a large in another, and even within a single brand, the fit can shift depending on the garment's intended use.

This guide breaks down how each brand actually fits, where the differences are, and how to make a confident decision when you can't try something on first.

The General Picture

All three brands design for hunters, but they approach fit differently based on their philosophy about layering and movement.

Sitka runs slightly generous in most categories. Their gear is designed with layering built into the cut, so a medium shell is meant to fit over a medium base layer and mid layer from their own system. If you're between sizes, your normal size will usually work — but if you're lean and don't layer heavy, you might find tops a bit roomy through the torso.

KUIU tends to run trimmer and more athletic. Their sizing is built around a closer-to-body fit, especially in base layers and mid layers. Outerwear has room for layering, but it's still a slimmer cut than Sitka overall. If you typically wear a large in most brands, you may want to size up in KUIU base layers and softshells.

First Lite splits the difference. Their base layers and mid layers fit true to size for most people, with a moderate athletic cut that isn't as tight as KUIU but isn't as generous as Sitka. Their outerwear tends to be roomy enough for layering without feeling oversized.

Upper Body: Chest Measurement Comparison

Size	Sitka Chest (in)	KUIU Chest (in)	First Lite Chest (in)
S	36–38	35–37	36–38
M	39–41	38–40	38–40
L	42–44	41–43	41–43
XL	45–47	44–46	44–46
2XL	48–50	47–49	47–49

Upper Body: Sleeve Length Comparison

Sleeve length is where a lot of hunters get surprised, especially when switching between brands. A jacket that fits perfectly in the chest can still leave your wrists exposed if the brand cuts sleeves short — or bunch at the cuffs if they run long.

Size	Sitka Sleeve (in)	KUIU Sleeve (in)	First Lite Sleeve (in)
S	33–34	32.5–33.5	33–34
M	34–35	33.5–34.5	34–35
L	35–36	34.5–35.5	35–36
XL	36–37	35.5–36.5	36–37
2XL	37–38	36.5–37.5	37–38

Sitka and First Lite run similar sleeve lengths, while KUIU tends to cut about half an inch shorter across the board. For taller hunters or anyone with longer arms, KUIU sleeves can feel noticeably short — especially in base layers where there's no cuff adjustment to compensate. If you're 6'2" or taller, pay close attention to sleeve length in KUIU and consider sizing up.

Pants: Waist and Inseam Comparison

Pants sizing is where the brands diverge the most from each other — and from what the tag says. Sitka pants are particularly notorious for running large in the waist.

Tagged Size	Sitka Actual Waist (in)	KUIU Actual Waist (in)	First Lite Actual Waist (in)
30	31.5–32	30–31	30.5–31.5
32	33.5–34	32–33	32.5–33.5
34	35.5–36	34–35	34.5–35.5
36	37.5–38	36–37	36.5–37.5
38	39.5–40	38–39	38.5–39.5

Sitka pants consistently measure 1.5–2 inches larger than the tagged waist size. A tagged 34 in Sitka's Dew Point or Mountain Pant will actually measure closer to 35.5–36 inches at the waist. Many experienced Sitka buyers size down one from their true waist measurement. KUIU pants run the truest to tagged size, and First Lite falls in between.

Standard Inseam Lengths

Brand	Standard Inseam	Tall Option	Notes
Sitka	32"	34" (select styles)	Regular/Tall offered in Mountain, Dew Point, Traverse
KUIU	32"	34" (select styles)	Attack and Guide pants offer tall inseams
First Lite	32"	Not widely available	Most styles are standard inseam only

Note: All measurements are approximate ranges based on published size charts and real-world fit reports. Actual measurements can vary between product lines within the same brand. Always check the specific garment's size chart when available.

A few things jump out from these tables. KUIU consistently runs about one inch smaller in the chest and half an inch shorter in the sleeves across the board. That doesn't sound like much on paper, but in practice it means a KUIU large fits more like a Sitka medium-to-large — especially in fitted pieces like the Peloton or Attack pants. Sitka gives the most room at every size and runs the most generous in the waist, which makes sense given their system-layering approach.

Where It Gets Tricky: Specific Garment Types

Base Layers: This is where the brands diverge the most. Sitka base layers (Core series) have a relaxed fit that some hunters find too loose for a next-to-skin layer. KUIU base layers (Peloton, Ultra Merino) fit snug and stretchy — size up if you don't like compression-style fit. First Lite base layers (Catalyst, Wick) fit true to size with moderate stretch.

Softshells and Mid Layers: Sitka's Jetstream and Stratus lines run generous. KUIU's Guide and Kenai are trimmer through the arms and torso. First Lite's Sawtooth and Kiln hover in the middle. If you're transitioning from Sitka to KUIU in this category, consider going up one size.

Outerwear and Rain Gear: All three brands build layering room into their shells, so the differences narrow here. A Sitka Thunderhead in large and a KUIU Yukon in large will fit more similarly than their respective base layers would. First Lite's Boundary Stormtight follows the same pattern. You can generally stick with your true size in shells across all three brands.

Pants: Sitka pants (Dew Point, Mountain) tend to run 1.5–2 inches large in the waist — size down. KUIU pants (Attack, Guide) run true to tagged size, making them the most predictable. First Lite pants are generally true to size with a slightly relaxed seat. Inseam lengths vary — Sitka and KUIU offer regular and tall in select styles, while First Lite is more standardized at 32 inches.

Practical Advice for Buying Used

When you're buying used gear and can't try it on, here's how to reduce your risk:

Measure a garment you already own. Lay a jacket or pant flat and measure the chest, sleeve length, and waist. Compare those numbers to the size chart of the brand you're looking at — not to the size label on your current gear. A "large" measurement from your Sitka Fanatic is more useful than the word "large."

Know which generation you're buying. Sitka in particular has adjusted their fit over the years. Older Sitka (pre-2018 or so) ran even more generous than current production. If you're buying a used Sitka piece from several years back, it may fit a half-size larger than the current equivalent.

Account for shrinkage. Merino-blend base layers from all three brands can shrink slightly with repeated washing, especially if they've been machine dried. Used merino that's been through dozens of wash cycles may fit tighter than it did new.

Ask the seller for measurements. On resale platforms, flat-lay measurements are far more reliable than the size on the tag. Chest width, back length, and sleeve length will tell you almost everything you need to know.

The Bottom Line

If you wear the same size across most outdoor brands, you'll likely fit into Sitka and First Lite at your usual size, and you may need to size up in KUIU — especially in base layers and mid layers. Sitka runs the most generous, KUIU runs the trimmest, and First Lite lands in between. For pants, Sitka runs large — size down one from your true waist.

The safest move when buying used is to ignore the tag entirely and work from actual garment measurements. Sizing labels are a starting point, not a guarantee — and when you're buying secondhand across multiple brands, the tape measure is always more honest than the tag.