What is the minimum tech pack a factory needs for underwear?

Short answer: A factory can quote a rough price from photos, but to quote accurately and make a sample that matches your idea, it needs a minimum set of information. The minimum underwear tech pack covers six points. First, a flat sketch of front and back showing style lines, seams, waistband and leg finishing. Second, a measurement chart for the base size, with how each point is measured and a tolerance; ISO 8559-1 defines body measurements, which helps when the brand also publishes size charts. Third, a bill of materials: main fabric with fibre composition and weight, lining or gusset fabric, elastic, thread and any trims. Fourth, construction details such as stitch types, seam positions and waistband attachment. Fifth, labels and packaging: brand label, size, care and fibre content labels and how many pieces per pack. Sixth, the destination markets, because label content depends on them. In the US, 16 CFR Part 303 sets rules for fibre content disclosure, and in the EU, Regulation 1007/2011 sets fibre names and labelling, while care symbols are defined in ISO 3758. Grading for other sizes and colourways can follow later, but the base size and materials should be clear before sampling.

The minimum six points

• Front and back flat sketch.
• Base size measurement chart with tolerances.
• Bill of materials.
• Construction details.
• Labels and packaging.
• Destination markets.

Useful but can follow later

• Full grading for all sizes.
• Colourway list and lab dip standards.
• Print artwork files.
• Carton and shipping marks.

What a factory can help with

• Suggesting fabrics and elastics.
• Converting a reference garment into measurements.
• Advising on stitch types.

A worked example

As an illustration, a brand could send a reference boxer brief it likes, a sketch of the changes, its target fabric and a list of markets, and ask the factory to return a measured spec for approval before sampling.

Version control

Give every tech pack a version number and date, and note changes on each sample round. Many sampling mistakes come from the factory and brand working from different versions.

Common gaps that cause delays

Missing tolerances, unclear measuring points, no elastic specification and no market list are the most common gaps. Each one leads to questions or a sample made on assumptions, which then needs another round. A short checklist sent with every new style helps avoid them.

Limits

A tech pack does not replace samples. Fit and comfort still need to be checked on bodies.

Facts, recommendations and uncertainty

Established: a factory needs a sketch, measurements, materials, construction, labels and markets to sample accurately. Recommendation: send these six points before asking for a sample. Uncertain: details that only become clear after the first fit session.

Sources and further reading

• ISO 8559-1:2017 — Size designation of clothes: anthropometric definitions for body measurement
• eCFR — 16 CFR Part 303, Rules under the Textile Fiber Products Identification Act (§303.43 tolerances, §303.3 fibres under 5%)
• Regulation (EU) No 1007/2011 — Textile fibre names and labelling
• ISO 3758:2023 — Care labelling code using symbols

Standards and regulations are referenced by their published scope. Test parameters, cycles and pass levels should be agreed with your laboratory for the specific product; legal requirements should be confirmed for each destination market.