A seal assembly (60; 160; 260; 360; 560) for a gas turbine engine comprising: a seal arc segment (66; 166; 266; 366; 466; 566) including a sealing portion (72; 372; 572), a first rail (74R-1; 374R-1) and a second rail (74R-2; 374R-4) opposed to the first rail (74R-1; 374R-1), the sealing portion (72; 372; 572) extending in a circumferential direction between opposed mate faces and extending in an axial direction between a leading edge and a trailing edge, each of the first and second rails (74R-1; 374R-1, 74R-2; 374R-4) extending outwardly in a radial direction from the sealing portion (72; 372; 572) to respective first and second edge faces (74RF-1, 74RF-2), and the sealing portion (72; 372; 572) including a sealing face (72A; 172A) dimensioned to bound a gas path and including a backside face (72C; 172C 372C; 472C) opposed to the sealing face (72A; 172A); wherein each of the first and second rails (74R-1; 374R-1, 74R-2; 374R-4) includes at least one interface bore (74B; 374B) dimensioned to receive a retention pin (84, 384) such that the seal arc segment (66; 166; 266; 366; 466; 566) is carried by the retention pin (84, 384) in an installed position, wherein the seal arc segment (66; 166; 266; 366; 466; 566) radially opposed to the sealing face (72A; 172A) between the first and second edge faces (74RF-1, 74RF-2) establishes a first region, the first region inclusive of a portion of the backside face (72C; 172C 372C; 472C) and the first and second edge faces (74RF-1, 74RF-2), the seal arc segment (66; 166; 266; 366; 466; 566) radially opposed to the sealing face (72A; 172A) between the leading and trailing edges (72LE, 72TE) establishes a second region, the first and second regions (BR1, BR2) extending circumferentially between the mate faces, the second region inclusive of the backside face (72C; 172C 372C; 472C) and the first region, and wherein a radially facing component of a total surface area of the first region divided by a radially facing component of a total surface area of the second region establishes a load ratio, and the load ratio is equal to or less than 0.5, characterised in that the first and second rails (74R-1; 374R-1, 74R-2; 374R-4) extends in the circumferential direction from and between the mate faces, wherein the sealing portion (72; 372; 572) includes a first cantilevered section between the first rail (74R-1; 374R-1) and the leading edge, and includes a second cantilevered section between the second rail (74R-2; 374R-4) and the trailing edge, the second region established along the first and second cantilevered sections (72L, 72T). a seal arc segment (66; 166; 266; 366; 466; 566) including a sealing portion (72; 372; 572), a first rail (74R-1; 374R-1) and a second rail (74R-2; 374R-4) opposed to the first rail (74R-1; 374R-1), the sealing portion (72; 372; 572) extending in a circumferential direction between opposed mate faces and extending in an axial direction between a leading edge and a trailing edge, each of the first and second rails (74R-1; 374R-1, 74R-2; 374R-4) extending outwardly in a radial direction from the sealing portion (72; 372; 572) to respective first and second edge faces (74RF-1, 74RF-2), and the sealing portion (72; 372; 572) including a sealing face (72A; 172A) dimensioned to bound a gas path and including a backside face (72C; 172C 372C; 472C) opposed to the sealing face (72A; 172A); wherein each of the first and second rails (74R-1; 374R-1, 74R-2; 374R-4) includes at least one interface bore (74B; 374B) dimensioned to receive a retention pin (84, 384) such that the seal arc segment (66; 166; 266; 366; 466; 566) is carried by the retention pin (84, 384) in an installed position, wherein the seal arc segment (66; 166; 266; 366; 466; 566) radially opposed to the sealing face (72A; 172A) between the first and second edge faces (74RF-1, 74RF-2) establishes a first region, the first region inclusive of a portion of the backside face (72C; 172C 372C; 472C) and the first and second edge faces (74RF-1, 74RF-2), the seal arc segment (66; 166; 266; 366; 466; 566) radially opposed to the sealing face (72A; 172A) between the leading and trailing edges (72LE, 72TE) establishes a second region, the first and second regions (BR1, BR2) extending circumferentially between the mate faces, the second region inclusive of the backside face (72C; 172C 372C; 472C) and the first region, and wherein a radially facing component of a total surface area of the first region divided by a radially facing component of a total surface area of the second region establishes a load ratio, and the load ratio is equal to or less than 0.5, characterised in that the first and second rails (74R-1; 374R-1, 74R-2; 374R-4) extends in the circumferential direction from and between the mate faces, wherein the sealing portion (72; 372; 572) includes a first cantilevered section between the first rail (74R-1; 374R-1) and the leading edge, and includes a second cantilevered section between the second rail (74R-2; 374R-4) and the trailing edge, the second region established along the first and second cantilevered sections (72L, 72T).