A private label period underwear line can be customized across fabric, absorbency, gusset length, sizing, waistband, color, labels, packaging, and test standards. Many brands use 3–5 functional gusset layers, with light-flow products often designed around 5–10 mL and higher-absorbency versions around 20–40 mL, depending on the test method. Main fabrics commonly contain 5–15% elastane for stretch, while body fabrics may range around 160–220 GSM. Before bulk production, brands should test wash shrinkage, colorfastness, leakage, absorbency, seam strength, and fit across several sizes rather than approving one sample size.

Private label development usually begins with the body fabric because it affects fit, recovery, drying time, hand feel, and sewing behavior. A cotton-elastane jersey may contain about 90–95% cotton and 5–10% elastane, while nylon or polyester performance fabrics may use 10–20% elastane to provide stronger stretch recovery for active products. Fabric weight can differ by style: approximately 160–190 GSM may suit lighter everyday underwear, while 190–230 GSM can provide more coverage and compression. The fabric should also be checked after repeated washing, because a 3–5% dimensional change can alter waistband tension and move the absorbent gusset away from the intended position.

That fit issue leads directly to gusset construction. Most period underwear uses several textile layers rather than one thick absorbent pad, and each layer has a separate job. A typical arrangement can include a moisture-transfer top layer, one or two absorbent textile layers, a waterproof or water-resistant membrane, and the outer body fabric. A brand targeting 10–15 mL capacity may need less absorbent material than one targeting 25–40 mL, but laboratory saturation capacity should not be presented as guaranteed wear time because pressure, body movement, fluid viscosity, and garment fit change real-world performance.

A useful specification separates “absorbency capacity” from “leak protection.” A garment can absorb 25 mL in a bench test and still leak during movement if the absorbent zone is too narrow or poorly positioned.

Gusset dimensions therefore deserve the same attention as material choice. Daywear products may concentrate protection around the central crotch, while overnight underwear often extends the functional area farther toward the rear waistband. A medium-size garment might use a gusset roughly 7–9 cm wide at selected points, but the final dimensions should come from fit trials rather than copying a generic pattern. For active products such as sport period underwear, movement control becomes more important because running, stretching, or cycling can shift the garment. Waist and leg openings often need firmer recovery while remaining comfortable during 30–60 minutes of continuous activity.

Sizing should then be developed around actual body and garment measurements instead of simply relabeling a factory’s existing S–XL range. A useful specification includes waist, hip, front rise, back rise, leg opening, side seam, crotch width, gusset length, and waistband height. If a range extends from XS to 3XL, at least 6 size points may require grading review. Testing only one medium sample is risky because the relationship between gusset position and anatomy changes as sizes increase. Many apparel brands use tolerances of roughly ±0.5–1.0 cm on selected finished measurements, although acceptable tolerance depends on construction and measurement location.

Size grading also affects elastic selection. A waistband that feels comfortable in size M may become too tight in XL if elastic length is graded too slowly, while a loose leg opening can allow movement around the gusset edge. Elastane content alone does not determine performance; elastic modulus, width, stitch tension, and recovery after washing also matter. After 5, 10, or 20 wash cycles, brands can compare waistband dimensions with the original sample and record percentage change. A 4% loss of recovery may be noticeable in close-fitting underwear even when the fabric still looks acceptable.

Color and surface design come next because dyeing and printing can change minimum order quantities. A supplier may allow stock black, beige, or navy in relatively small runs, while custom-dyed fabric can require hundreds of kilograms depending on the mill. If one garment uses 0.20–0.30 kg of fabric, a 200 kg dye lot could theoretically support several hundred units before cutting waste is included. Colorfastness should be checked against the intended care method, especially for dark colors. Standards from organizations such as AATCC and ISO have been widely used for textile colorfastness and dimensional-change testing for decades, including current apparel programs in 2026.

Matching a digital color on a monitor is not enough. Main fabric, elastic, sewing thread, mesh, and labels can all reflect the same shade differently because fiber composition and surface texture affect dye appearance.

Branding choices can remain simple while still looking custom. Common options include heat-transfer labels, woven labels, printed care labels, custom jacquard elastic, hangtags, and printed packaging. Heat-transfer labels reduce extra seam bulk, while woven labels may provide a more traditional garment finish. Care information should match the actual fabric and membrane system. If testing shows that tumble drying at higher heat shortens membrane life, the packaging and sewn-in label should not use generic care instructions. In the United States, textile fiber identification and care labeling have long been regulated through federal requirements, so label copy should be reviewed for the sales market rather than copied from another product.

Packaging should be specified at the same time because it affects unit cost, carton volume, and retail handling. A single folded brief may fit into a compact paper sleeve or box, while a 3-pack needs more space and a different barcode structure. If a master carton holds 60 units instead of 48 after packaging dimensions are reduced, carton efficiency increases by 25%. For an order of 6,000 units, that difference can reduce the number of cartons from 125 to 100, before allowing for actual packing constraints. Small packaging changes can therefore affect storage and freight calculations.

Manufacturing cost is usually spread across more variables than garment quantity alone. A program with 3 colors, 6 sizes, and 2 absorbency levels already creates 36 SKU combinations. If a 3,600-unit order were divided equally, each SKU would average only 100 units. Suppliers may set minimums by fabric color, elastic color, style, or packaging component rather than by total order quantity. Asking where every MOQ applies prevents a brand from assuming that one 3,000-piece order automatically qualifies for 10 colors and a full extended-size range.

Sampling should reduce that complexity before production starts. A practical sequence may include a prototype, fit sample, revised sample, size-set sample, and pre-production sample. Fit testing can include at least 3 body types within a selected size and more testers when budget allows. For a six-size range, testing the smallest, middle, and largest sizes provides more information than testing only M. Measurements, leakage observations, comfort comments, and wash results should be recorded in the same specification file so later revisions can be compared against version 1, version 2, and the approved production sample.

Performance testing should cover more than total liquid uptake. Brands can request absorbency, rewet, leakage resistance, waterproof performance, seam strength, dimensional stability, colorfastness, pilling, and repeated-laundering checks. A test after 20 or 30 wash cycles can reveal changes that a new sample will not show. If antimicrobial, PFAS-related, recycled-content, or other material claims are planned, the required test method and documentation should be agreed before production. Claim wording should match the test scope; a result from one fabric layer should not automatically be presented as a claim for the complete garment.

Production inspection should then compare bulk goods with the approved pre-production sample rather than relying on visual checks alone. Inspectors can verify measurements, stitching, gusset alignment, label position, color consistency, packaging, and random functional samples from several cartons. Apparel inspections often use AQL-based sampling plans, where the sample quantity increases with lot size and the buyer sets acceptable defect limits. For a production run containing several thousand garments, checking only 5 or 10 pieces provides little statistical coverage compared with a structured sampling plan.

Material traceability also becomes important when the collection uses recycled fibers, certified textiles, or specially specified membranes. Purchase orders should identify fabric code, composition, color, GSM, supplier, and production lot. If a later batch shows a 6% shrinkage rate compared with 2% in the approved fabric, lot records make investigation much easier. The same approach applies to elastic, bonding film, absorbent textiles, and waterproof layers because replacing one internal material can change the behavior of the finished underwear even when the exterior looks identical.

A scalable range usually uses shared components wherever performance allows. For example, 4 silhouettes can share the same black body fabric, care label, packaging size, and waistband construction while using different gusset lengths or absorbency levels. If each style instead uses 4 unique colors, 7 sizes, and separate packaging, the collection reaches 112 SKU combinations before multipacks are added. Standardizing selected materials reduces inventory fragmentation while leaving enough room to differentiate fit, coverage, color, and absorbency.

For brand owners, the most useful factory specification is a measurable one: fabric composition, GSM, finished measurements, tolerance, elastic type, gusset dimensions, layer construction, target absorbency, color reference, test requirements, labels, and packaging should all appear in the tech pack. A request such as “make heavy-flow underwear with soft fabric” leaves too many variables open. A specification stating 180 GSM body fabric, 8% elastane, 25 mL target laboratory capacity, extended rear gusset, six sizes, and wash testing through 20 cycles gives the supplier a much clearer production target.