A fabric spec sheet — also called a fabric specification sheet, textile spec, or lab dip report attachment — is a technical document that communicates the physical and chemical properties of a fabric. Manufacturers and suppliers provide it to B2B buyers as part of the pre-production process, and it serves as the formal agreement on what the fabric must deliver.
For blank apparel buyers — whether you run a print shop, own a clothing brand, or manage procurement for a distributor — the spec sheet is your primary tool for verifying that a fabric will meet your product standards before you commit to a bulk order. Unlike a physical sample, which only shows you one moment in time, a spec sheet defines consistent performance targets that every production batch must meet.
A complete fabric spec sheet typically includes:
GSM — grams per square meter — is one of the most discussed spec sheet parameters, and for good reason. It is a direct measurement of fabric weight that influences how a garment feels, how it drapes, how durable it is, and how well it accepts prints.
To measure GSM, manufacturers cut a 1m × 1m square of fabric and weigh it on a precision scale. The result is a single number that tells you how heavy the fabric is per unit area. Unlike ounce-per-square-yard (oz/sqyd), which is common in US domestic fabrics, GSM is the international standard and the metric used on most Asian supplier spec sheets.
| Garment Type | Typical GSM Range | Characteristics |
|---|---|---|
| Lightweight T-shirts / Summer tops | 120 – 150 gsm | Light, breathable, drapey; may show print ink prominently |
| Standard T-shirts | 150 – 180 gsm | Balanced weight, good durability, standard for most blank tees |
| Premium / Heavyweight T-shirts | 180 – 220 gsm | Substantial feel, less drape, excellent print base |
| Light hoodies / Sweatshirts | 260 – 300 gsm | Comfortable weight, suitable for layering |
| Heavyweight hoodies | 320 – 400 gsm | Premium weight, maximum durability, cozy feel |
| Polo shirts | 160 – 220 gsm | Varies by fabric type; pique knit typically 180-200 gsm |
When you see GSM on a spec sheet, also check the Construction field — a 180 gsm single jersey and an 180 gsm French terry feel completely different because of their knit structures. GSM alone does not tell the whole story.
For print shops and brands using screen printing or DTG (direct-to-garment), GSM affects ink laydown and print sharpness. Lighter GSM fabrics (120-150) can result in more show-through of ink, which may be desirable for discharge printing but problematic for bold, opaque plastisol prints. Heavier GSM fabrics (180-220) provide a more stable print surface with better ink holdout.
Color fastness refers to a fabric's ability to resist color change or color transfer under various conditions. It is one of the most common sources of B2B buyer complaints because poor color fastness leads to dye bleeding onto other garments, fading after a few washes, and fabric that looks washed out or dull prematurely.
Color fastness is not a single test — it is a family of tests, each measuring resistance to a different stressor. A complete spec sheet should include results for at least three types:
Measures how much color transfers or fades when the fabric is laundered under standard conditions. Rated on a 1-5 scale where 5 = no change. For most B2B applications, wash fastness of Grade 3 or higher is acceptable; Grade 4 or 5 is excellent.
Measures color transfer from fabric to another surface through rubbing — both dry and wet. Rated on the same 1-5 scale. This is especially important for dark-colored garments and for fabrics that will be worn or layered with light-colored items. Grade 3 dry and Grade 2-3 wet are minimums for most buyers.
Measures resistance to color change when exposed to light — critical for garments displayed in store windows or exposed to sunlight. Rated on a 1-8 scale where 8 = no fading. For most apparel, Grade 4 is the minimum acceptable level.
| Color Fastness Test | Industry Standard | Acceptable for B2B | Excellent for B2B |
|---|---|---|---|
| Wash Fastness | AATCC 61 / ISO 105-C01 | Grade 3 | Grade 4–5 |
| Dry Crocking | AATCC 8 / ISO 105-X12 | Grade 3 | Grade 4–5 |
| Wet Crocking | AATCC 8 / ISO 105-X12 | Grade 2–3 | Grade 3–4 |
| Light Fastness | AATCC 16E / ISO 105-B02 | Grade 4 | Grade 5–6 |
Be aware that color fastness requirements for reactive dyeing (common on cotton fabrics) and disperse dyeing (common on polyester) are different. Reactive-dyed cotton generally achieves higher wash fastness grades than disperse-dyed polyester, but polyester typically has superior light fastness.
Stretch and recovery specifications apply primarily to knit fabrics that contain elastic fibers (elastane, spandex, Lycra) and to performance or athletic apparel. If you are sourcing standard 100% cotton T-shirts, stretch and recovery specs are less relevant — but for polo shirts, athletic wear, or fitted garments, they are critical.
When a spec sheet lists stretch as "20% × 30%" with "95% recovery," here is how to interpret it:
| Elastane Content | Typical Stretch Range | Typical Recovery | Best Use Cases |
|---|---|---|---|
| 0% (no stretch) | 0–5% | N/A (woven) | Standard T-shirts, formal wear |
| 3–5% | 10–15% | 90–93% | Light comfort stretch, casual wear |
| 5–8% | 15–30% | 93–96% | Activewear, fitted garments |
| 8–12% | 30–50% | 95–98% | High-performance athletic wear |
One common problem B2B buyers encounter is ghost stretching — when a fabric with marginal recovery is made into a fitted garment, the fabric gradually bags out after wearing and washing. If recovery is below 90%, you will see this effect within a few wash cycles. Always ask for a stretch and recovery test report when sourcing fitted or athletic apparel.
Here is a practical walkthrough of reading a real fabric spec sheet for a typical blank T-shirt order:
Reading this as a buyer: the fabric is a medium-weight 100% cotton jersey with acceptable all-around color fastness for print-and-wear applications. The shrinkage of ±5% is the notable risk — you should budget for this in sizing and advise customers accordingly. The pH range (5.5–7.0) indicates the fabric is within the neutral-to-slightly-acidic range, which is important for skin contact and for print preparation.
Not all suppliers volunteer spec sheets proactively. Here is how to request one:
All images in this article are from free stock libraries.