A felled seam, sometimes called a flat felled seam, is a way of joining two pieces of fabric so that the raw edges are folded over and enclosed within the seam itself, then secured with two visible rows of stitching, rather than being left exposed on the inside of the garment. This is a common construction detail on the inner and outer leg seams of jeans.
Because the raw edges are fully enclosed, a felled seam does not fray with washing and wear the way a simple, single row seam can, which makes it noticeably more durable for a garment that is stressed and washed as often as jeans. The double row of visible stitching, often in a contrasting orange or gold thread, is also a recognisable part of jeans' traditional workwear look.
Checking that leg seams are felled, flat and evenly stitched is a useful way to judge how well made a pair of jeans is before buying. See our buying guide for more construction details to look out for, and denim guide for background on the fabric these seams are built to withstand.
