How do I specify inseam and leg opening on boxer briefs?

Main answer

Inseam sets the leg length of boxer briefs, and leg opening sets grip and comfort, so define both as measured values with a tolerance, state whether the opening is measured relaxed or stretched, and check the sample on real wearers across the size range. Leg length alone cannot describe how a boxer brief feels or stays in place.

Inseam

Inseam is the length from the crotch seam down the inside leg to the hem. Brands often call lengths short, mid or long, but the numbers vary, so give the measurement for each size. Leg length also changes with grading, since larger sizes need longer legs. Say whether the number includes the leg band.

Leg opening

Leg opening is measured flat across the hem, relaxed, and sometimes also stretched, because the way it grips is part of comfort. A tight opening rolls and cuts into the thigh. A loose one rides up. The right value depends on fabric stretch, elastane share, and whether there is a grip band or elastic. ASTM D2594 relates to testing the stretch of knit fabrics.

Grading and fit by size

Thigh circumference grows with body size faster than leg length, so grade the opening more than the inseam. Check that the smallest and largest sizes do not squeeze or sag. Test the sample on different thigh shapes, since athletic builds change the result compared with slim builds.

Leg bands and grip

Some boxer briefs use an elastic grip band or a silicone strip to keep the leg in place. These add cost and can mark skin, so ask what is used and test it on several thigh shapes. A plain hem relies on fabric stretch alone to stay down.

Writing the spec

Include inseam, leg opening relaxed, leg opening at a stated stretch, leg band width and tolerance for each size. Add a diagram with the points marked. Request wash-tested measurements. See underwear fit and construction and boxer brief manufacturer.