The Ultimate T-Shirt Spec Sheet

We’ve long followed Shift Fashion Group's YouTube channel for their deep-level expertise in clothing manufacturing. Their recent deep dive into T-shirt anatomy is the most comprehensive guide we’ve seen to date, so we’ve summarized the content here (and added a bit more) to help you audit your next purchase.

Joe knows it all

The Fiber

This is the foundation. Without good fibers, you can't build a decent garment. Here are a few things to look for:

Staple Length: The longer the fiber, the smoother and stronger the yarn. Look for Extra-Long Staple (ELS) like Pima or Egyptian Giza.

Micronaire: This measures fiber fineness. 3.7 to 4.2 is the industry standard for a high-quality, mature fiber.

Tenacity: Measures fiber strength. You want a rating above 35 to ensure the shirt doesn't lose its integrity after a few washes.

Cotton Types:

• Upland: The standard mass-market option.

• Pima/Giza/Sea Island: Premium specialty fibers.

• CVC Blend: A mix of cotton and polyester used to, mostly, cut costs.

  
  

Yarn Production

Once the fiber is harvested, it has to be turned into yarn. This is where most "budget" brands cut corners.

Singles Count: A 30–40 count is the sweet spot for a high-quality tee. Higher counts (60+) are reserved for very fine, dressier garments.

Ply: High-quality yarn often uses 2-ply (two strands twisted together) for significantly better strength.

Carded vs. Combed: Most garments stop at carding (aligning fibers). For a truly premium shirt, you want combed cotton, which removes short, weak fibers and impurities.

Spinning Methods:

• Open-end: Lower quality, rougher texture.

• Ring-spun & Compact: The most popular method for high-end basics.

• Vortex (MVS): Results in a stronger, pill-resistant yarn, though it can feel stiffer.

Cotton yarn

The Knit

How the yarn is knitted determines the drape, breathability, and structural integrity of the shirt. A high-quality shirt uses a tight, fine knit that provides a dense structure without needing excessive weight. A light, tightly-knit shirt will always outlast a heavy, loosely-knit one.

Common Knit Structures:

• Single Jersey: The industry standard. It’s a single-layer knit that is lightweight and breathable. However, because it only has one "face," it is prone to curling at the edges and can lose its shape more easily than double-knits.

• Interlock: A "double-knit" construction where two layers of jersey are knitted together. The result is a fabric that looks the same on both sides. It is significantly more stable, heavier, and smoother than standard jersey. If you want a shirt that doesn't "bag out" at the hem, look for interlock.

• Rib Knit (1x1 or 2x2): Characterized by vertical ridges. While rarely used for the full body of a premium T-shirt, it is the essential choice for collars and cuffs because of its high elasticity and "recovery" (the ability to snap back after stretching).

• Piqué: Often associated with polo shirts, but occasionally used for textured tees. The "honeycomb" or "diamond" pattern increases surface area, making it highly breathable and better at hiding sweat.

Grams per Square Meter (GSM) is a common industry term, but it is often used as a "trap" for the uninformed. A high GSM simply means the fabric is heavy; it does not mean it is well-made. A manufacturer can achieve a high GSM by using thick, low-quality yarn with a loose knit tension.

Dyes and Finishes

Manufacturers use chemistry to add colors and to make a shirt look better than it actually is. You should know how to spot the tricks.

Dye Types:

• Pigment dyes: Pigment particles are too large to enter the tiny pores of a fibre. They require a binder (a type of glue or resin) to hold them onto the surface

• Sulphur dyes: Cheap and effective, these dyes are initially insoluble but are chemically "dissolved" using a reducing agent (like sodium sulfide) so they can slip into the fibre's interior. Once inside, they are oxidized (exposed to air or chemicals) to become insoluble again, effectively trapping the colour inside the fibre

• Reactive dyes: Change the molecular structure of the cotton.

Finishing Processes:

• Silicone Emulsion: This is a "cheat." It coats the fibers to make them feel premium in the store, but washes off in the first cycle.

• Bio-enzyme Wash: Uses enzymes to "digest" surface fuzz for a clean, permanent finish.

• Mercerization: A chemical process using liquid ammonia that makes fibers smoother, shinier, and stronger.

Construction and Architecture

This is the engineering of the shirt's design. Even the best materials in the world won't make you look good if the fit isn't right.

The Neckline: Look for a 2x2 rib for better recovery and 3-5% Lycra content to prevent "bacon neck."

Shoulder Seams: Ensure there is shoulder-to-shoulder taping to prevent the shirt from stretching out at the seams.

Armholes: Premium shirts feature higher, tighter armholes. This allows you to move your arms without the entire shirt lifting.

Side-Seamed vs. Tubular: Tubular shirts, without side seams, have a heritage feel but are more prone to torquing. Side-seamed shirts allow for a tapered, ergonomic fit that follows the human torso.

A good shoulder fit

The Final Audit: Quality Control

Before heading to the register, look for these markers of professional craftsmanship.

Stitches Per Inch (SPI): Fast fashion uses 6–8 SPI. You want 10–12 SPI for a flexible, durable seam.

Stitch Type: Flatlock stitching is the elite choice, as it joins fabric edge-to-edge with zero bulk, making it the most comfortable against the skin.

AQL (Acceptable Quality Level): Premium brands operate at an AQL of 1.5 to 2.5. This means they have a near-zero tolerance for minor defects, like loose threads or uneven hems.

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If you want to learn more about how to upgrade your t-shirt game, take a look at this post.