Starting a private label period underwear brand begins with a narrow product brief: target wearer, absorbency level, body fabric, gusset construction, size range, retail price, and first-order quantity. A first range with 2 styles, 2 colors, and 6 sizes creates 24 SKUs; at 50 units per SKU, inventory already reaches 1,200 pieces. Before production, brands should approve fit samples, wash performance, absorbency, chemical testing, labeling, packaging, and landed cost. In a 2025 study of 43 period underwear products, 11 samples, or 26%, contained at least 1,000 ppm total fluorine, showing why material testing should be specified before bulk manufacturing.

A new brand should start with the customer use case before choosing lace, colors, or packaging. Daytime backup underwear, overnight high-absorbency briefs, teen products, period swimwear, and seamless office styles need different gusset lengths, rises, fabrics, and price points.

Keep the first range small enough to measure demand. Two styles × two colors × six sizes gives 24 SKUs; four styles × four colors × seven sizes creates 112 SKUs. At only 40 pieces per SKU, the second range requires 4,480 units before one pair has been sold.

That SKU count should feed into the supplier brief. Give the factory a written specification covering body-fabric composition, fabric weight, stretch, waistband width, front and back rise, gusset width, absorbency target, label type, packaging, size measurements, and acceptable tolerances.

A quotation without a fixed specification is not comparable. A $4.80 pair using a standard polyester body and a $6.20 pair using a heavier nylon-elastane body, longer absorbent zone, custom elastic, and printed care label are different products.

The gusset should be treated as a functional textile system rather than a marketing feature. A reusable underwear product commonly contains three to five layers, although a 2025 ACS study examining reusable feminine hygiene products found constructions ranging from 3 to 8 layers, with an average of four layers.

A typical construction may combine a moisture-facing layer, one or more absorbent layers, a liquid-resistant layer, and the outer fabric. Adding material can raise capacity, but it can also increase thickness, heat retention, drying time, sewing difficulty, and cost, so capacity should be tested as a finished garment.

Ask the supplier to state how absorbency was measured. “Heavy flow” is too vague for product development. Record the test liquid, volume, application rate, test area, conditioning method, number of specimens, leakage endpoint, and whether the result represents one sample or an average.

For internal development, five to ten specimens per construction are more useful than testing one pair. If 10 samples absorb 35–41 mL before leakage, the range tells you more about production consistency than a single 40 mL result.

Fabric choice comes next because the body fabric affects fit as much as comfort. A common stretch underwear body may contain 8–20% elastane, while the remaining fiber can be nylon, polyester, cotton, modal, or another blend, depending on the supplier and product position.

Compare fabric by measurable properties rather than hand feel alone:

• composition and GSM;

• width and usable width;

• four-way or two-way stretch;

• recovery after extension;

• shrinkage after repeated washing;

• pilling and abrasion performance;

• colorfastness to washing and perspiration;

• minimum dye lot per color.

A fabric can feel excellent in the first sample and fit poorly after 20 washes. The next step should therefore combine fit testing and wash testing instead of approving appearance on day one.

Use testers from several sizes rather than approving the whole range on a medium sample. If the launch covers XS–2XL, fitting at least three points in the range—such as S, L, and 2XL—can reveal grading problems that one middle-size sample cannot show.

Record waist, hip, front rise, back rise, leg opening, side seam, gusset width, and gusset length before and after washing. A 3% dimensional change on a 70 cm circumference is 2.1 cm, enough for a wearer to notice in close-fitting underwear.

Wear testing should use a simple form with the same questions for every participant. A small pre-production panel of 20 wearers can still produce useful product feedback when size, flow level, wearing time, activity level, leakage position, wet feeling, waistband movement, and drying time are recorded consistently.

“Did you like it?” produces weak product information. “After six hours, did leakage occur at the front, back, side, or not at all?” can be compared across 20 wearers.

Material testing deserves separate attention because reusable menstrual products stay in close skin contact for hours. In a 2025 ACS study, researchers screened 59 reusable feminine hygiene products, including 43 period underwear products, and analyzed 323 individual textile samples across product layers.

Among the 43 period underwear items, 11, or 26%, contained at least 1,000 ppm total fluorine. Across all 59 products, 19 were selected for targeted analysis of 42 PFAS compounds, and at least one PFAS was detected in every extracted product. The authors also found products without levels associated with intentional fluorination.

Brands making PFAS-free or similar chemical claims should therefore ask what was tested, which laboratory performed the work, which test method was used, what detection limits applied, and whether the report covers the finished garment, one fabric, one color, or one production lot.

Certification scope matters for the same reason. OEKO-TEX STANDARD 100, for example, was updated in its 2026 edition and uses product classes and substance limits based on intended skin contact. A supplier saying “our fabric is certified” is not the same as showing that every relevant component in the finished underwear is covered.

Once materials are fixed, labeling has to match the sales market. In the United States, the FTC requires most textile products to disclose fiber content, country of origin, and the identity of the manufacturer or another responsible business. Fibers representing 5% or more of total fiber weight generally need to be identified by generic name.

The FTC Care Labeling Rule also requires manufacturers and importers to provide regular care instructions and to have a reasonable basis for them. The current rule has been effective since September 1, 2000, and care information must remain legible through the useful life of the garment.

That requirement should shape wash testing before label artwork is approved. If the factory recommends “machine wash cold, line dry, no bleach,” the brand should retain testing or other reliable support for the instruction rather than copying care wording from another label.

Costing follows because the approved construction determines whether the commercial model still works. Consider an illustrative order of 1,200 units with a $5.40 factory price.

Cost item	Per unit
Garment	$5.40
Labels and printed insert	$0.18
Retail packaging	$0.42
Inspection allocation	$0.12
Freight and import allocation	$0.88
Estimated landed cost	$7.00

At a $28 retail price, $7 landed cost equals 25% of selling price, leaving 75% before fulfillment, payment fees, discounts, returns, marketing, payroll, and overhead. A 20% promotion lowers the selling price to $22.40 while the $7 landed cost stays unchanged.

MOQ should therefore be discussed by color, style, fabric, and custom component, not only as one total number. A supplier advertising a 500-piece MOQ may mean 500 pieces per color; three colors would require 1,500 pieces.

Ask whether sizes can be mixed inside the MOQ and whether the factory imposes a minimum quantity for custom elastic, dyed fabric, printed packaging, or bonded gusset material. A garment MOQ of 500 pieces is less useful if the custom waistband supplier requires 3,000 meters.

Before paying the bulk-production deposit, approve a pre-production sample with signed measurements, materials, color references, labels, packaging, seam construction, gusset dimensions, and workmanship standards. Keep one approved unit with the brand and one with the factory.

AQL inspection can then be discussed with the supplier or inspection company. The acceptable level should fit the product and contract; the larger point is to define what counts as a major or minor defect before thousands of pairs are packed.

Inventory planning should remain tied to size demand. Equal buying across XS–2XL may look simple, but demand rarely distributes evenly. If a 1,200-unit order uses a planned ratio of 10% XS, 20% S, 30% M, 22% L, 12% XL, and 6% 2XL, the order becomes 120, 240, 360, 264, 144, and 72 units.

The first order can then generate usable reorder data. Track sell-through by size, color, and style; fit-related returns; leakage complaints; repeated wash complaints; and product defects separately rather than putting every return into one category.

Packaging should answer the questions that reduce avoidable customer service: absorbency range, intended use, fabric composition, size, wash method, drying method, and expected replacement conditions. Avoid printing an exact tampon-equivalent claim unless the comparison has a documented test basis.

For online sales, photograph the front, back, side, waistband, gusset length, gusset width, fabric texture, and fit on more than one body size. If 30% of customer messages concern sizing, a better measurement table and model-size reference may reduce more service work than another lifestyle photograph.

A sensible first production calendar can allocate 2–4 weeks for samples and revisions, 2–3 weeks for material preparation, 4–8 weeks for bulk manufacturing, and additional time for inspection and freight. Custom dyeing, packaging, laboratory work, and peak-season factory capacity can extend those ranges.

Do not set the public release date from the supplier’s best-case production estimate. Set it after materials are confirmed, the pre-production sample is approved, and the factory has issued a production schedule.

For the first release, 2 styles and 2–3 colors are usually easier to read than a broad collection. A smaller range gives each SKU enough units to show whether customers prefer a silhouette, size, absorbency level, or color rather than scattering 1,000–2,000 units across dozens of low-volume combinations.

After the first 100–300 customer orders, compare repeated comments with manufacturing data. If 18% of size exchanges come from one style, inspect that style’s measurements and grading before adding more colors; if leakage feedback clusters at the rear, review gusset length before increasing absorbent thickness.

The next production order can then change one measurable item at a time—rise, leg opening, gusset length, fabric weight, absorbent layer, waistband tension, or size grading—while keeping enough of the original specification unchanged to see whether the revision improved customer results.