What should I check on an underwear fit sample?

Short answer: A useful fit sample review covers three things: whether the sample matches the specification, whether it fits and moves well on a real body, and whether it keeps its fit after washing. Check measurements first against the specification with tolerances, then fit the sample on a fit model in the target size while walking, sitting and bending, and then wash and re-measure. Record every comment with a measurement or a clear location, take photos and send consolidated feedback. Approve only when changes from the previous round have been confirmed, not just promised.

Before the fitting

• Confirm the sample is in the correct fabric, or note if it is a substitute.
• Check the size label and style code.
• Measure every point on the specification, with the garment laid flat and relaxed.

Measurements to check

• Waist relaxed and stretched.
• Front and back rise.
• Leg opening relaxed and stretched.
• Inseam or leg length for boxer briefs.
• Pouch depth and width, gusset width and length.
• Waistband width.

Compare each with the tolerance agreed, and highlight anything outside it.

Fit on the body

Fit on a model who matches the size chart. Check:

• Waistband: sits level, does not roll or dig, stays up when bending.
• Legs: no digging, no ride-up after walking, no gaping.
• Pouch: support without pressure, no wrinkles or excess fabric.
• Seat: covers well, no pulling at seams.
• Seams: no rubbing, especially inner thigh and crotch.

Base model measurements on consistent body points such as those defined in ISO 8559-1.

Stretch and recovery

Stretch the waistband and leg openings by hand to the working extension and check for popped stitches and recovery. For objective comparison of elastics, a tension and elongation method such as ASTM D4964 can be used.

After washing

Wash the sample and measure again using a method such as ISO 5077. Note any shrinkage, twisting or seam distortion and refit if changes are significant.

Documentation

Record measurements, comments and photos in one sheet per sample round. Give clear instructions such as "increase leg opening by 1 cm", not "leg feels tight". Keep the approved sample as a sealed reference.

Limits

One fit model does not represent every customer. Check extreme sizes before production.

Facts, recommendations and uncertainty

Established: a fit review should check measurements, fit on a body and behaviour after washing. Recommendation: use one structured sheet and clear measurable comments. Uncertain: how the fit will suit the full customer range until size sets are tested.

Sources and further reading

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

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.