The striped rib-knit open-front cardigan is listed in Black, with S, M and L options. Its product chart gives the same 20-inch sleeve for all three sizes, while shoulder width changes from 22 to 23 to 24 inches. Because the shoulder seam is dropped, the sleeve column alone does not tell you where the cuff will land.

Measure shoulder and sleeve together

Lay a cardigan you own flat and identify the seam where its sleeve begins. Record the width between shoulder seams, then the seam-to-cuff sleeve length. Compare both measurements with this listing, using the same endpoints if the seller confirms them. The listed pairs are S: 22-inch shoulder and 20-inch sleeve; M: 23 and 20; L: 24 and 20. The seam can sit farther out as the shoulder width grows even though the sleeve number stays unchanged.

As a rough planning calculation, half of a one-inch increase in total shoulder width adds about half an inch on each side before the sleeve begins. That makes the S-to-M and M-to-L shoulder steps relevant to reach. It is not a promised cuff position: the neckline, seam angle, drape and measurement method are unreported. If your reference cardigan has a different shoulder construction, ask for a shoulder-seam-to-cuff photograph or a worn view of the exact size.

Check the open-front layer separately

The chart lists bust as 41, 43 and 45 inches for S, M and L. It also lists length as 32, 32 and 33 inches. Compare those garment figures with an open cardigan that already accommodates your intended shirt. An open front need not close over the chest, so the bust figure does not prove front coverage; look at the gap and side drape in the selected size. Check the hem position against your reference piece before choosing a larger size only for sleeve reach.

The listing calls the knit moderately stretchy and says it is 100% acrylic, but gives no measured stretch range, armhole depth or cuff opening. It specifies hand washing cold and no tumble drying. Choose by the shoulder, sleeve, bust and length together, then resolve the missing measurement endpoints if a precise cuff or layer fit is important.