How should a jockstrap pouch be sized across S to XXL?

Short answer: A jockstrap pouch should not be scaled up at the same rate as the waistband. The waistband and straps follow waist and hip girth, which change a lot across sizes, while the anatomy the pouch holds varies much less between sizes. Scaling the pouch proportionally usually makes it too loose and unsupportive in the largest sizes, or too small in the smallest. Most patterns grade the pouch in smaller steps than the waistband, sometimes keeping one pouch for two sizes, and adjust its width at the base to match the leg straps and the wider body in large sizes.

What changes with size

• Waistband length: graded with waist girth.
• Strap length: graded with hip and seat shape, because the straps run from waistband to leg crease.
• Pouch base width: often grows a little, so the pouch connects smoothly to straps set further apart.
• Pouch depth and height: usually grow in small steps, if at all.

Pouch shape

A contoured pouch with a centre seam or shaped panels supports better than a flat triangle. Depth, the curve of the centre seam and the stretch of the fabric decide how much room there is. A pouch fabric with good recovery keeps its shape; one that grows during wear loses support.

Fabric and lining

Many jockstrap pouches use two layers or a firmer knit for support. Measure the fabric's stretch and recovery, for example with a tension and elongation method such as ASTM D4964 used for elastic fabrics, so that grading decisions are not undone by a stretchier lot later.

Fit testing across sizes

Fit-test every size if possible, at minimum the smallest, base and largest. Ask testers about support, pressure and whether the pouch stays in place while walking and sitting. Do not rely on mannequins, which do not show pouch fit well. Base waist and hip points on consistent definitions, such as those in ISO 8559-1, so grading is repeatable.

Washing

Wash and measure according to a method such as ISO 5077, since pouch fabrics and elastics can shrink at different rates and change pouch shape.

Communicating size

Publish the waist measurement for each size, because customers choose a jockstrap mainly by waist. If the pouch is designed to be roomy or compact, say so in the description.

Limits

Customer preference for a snug or roomy pouch varies widely. Testing with your target customers is the only way to set final dimensions.

Facts, recommendations and uncertainty

Established: the waistband and straps follow body girth while the pouch varies much less across sizes. Recommendation: grade the pouch in smaller steps and fit-test the extremes. Uncertain: the preferred pouch volume for your customers.

Sources and further reading

• ISO 8559-1:2017 — Size designation of clothes: anthropometric definitions for body measurement
• ASTM D4964 — Tension and elongation of elastic fabrics
• ISO 5077:2007 — Determination of dimensional change in washing and drying

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.