In a drop-shoulder tee the shoulder seam sits down on the upper arm instead of at the edge of the shoulder. The sleeve is shorter and wider, the armhole is deeper, and the body is usually boxy. The style looks simple, but every measurement that depends on the shoulder point changes, so the spec has to be explicit.

Define the points of measure

Write down where each measurement starts and ends. Shoulder drop is the distance from the neck-shoulder point to the shoulder seam, so say which reference you use. Sleeve length can be measured from the shoulder seam or from the neck point, and the two methods give very different numbers on a drop-shoulder tee. Add chest or body width, body length, armhole depth and sleeve opening. Attach a sketch showing each line.

Grade by size, not by percentage

Drop-shoulder styles are often cut oversized, but the proportions still need grading. If body width grows by a set step between sizes while shoulder drop and sleeve length stay fixed, small sizes look swamped and large sizes look short in the sleeve. Ask the factory for the grade rules and compare the smallest, middle and largest size on a body or form, not just on a table.

Fabric weight and drape

A boxy tee relies on fabric that holds its shape. Check weight with ASTM D3776 and compare it against the approved sample, because a lighter fabric can collapse at the shoulder and a heavier one can hang stiffly. Note the knit direction on the sleeve and body so the lines run straight.

After washing

Wash finished samples with a named procedure such as ISO 6330, then re-measure body width, body length, sleeve length and shoulder drop. Dimensional change can be measured with ISO 5077, and twist after laundering with AATCC TM179. A tee that grows in width or shortens in length can lose the proportions you designed.

What to approve

Approve a pre-production sample in at least two sizes, with a measured spec sheet, a washed measurement record and the final grade rules. Keep the washed approved sample as the reference for bulk.

Ask the factory to mark the shoulder seam position on a flat sketch of the approved sample and photograph the sample on a form from the front and side. Photos taken the same way for bulk make later comparison easier, and they settle disagreements quickly if a lot arrives with a different shoulder line.