On Center (OC)
Affiliate link — we may earn a commissionOn center (abbreviated OC or o.c.) is a framing measurement taken from the center of one stud or joist to the center of the next. 16 inches on center means the distance between the middle of one stud and the middle of the adjacent stud is 16 inches. Since a 2x4 is 1.5 inches wide, the gap between studs at 16-inch OC is actually 14.5 inches. Building codes specify OC spacing: 16 inches for most load-bearing walls, 12 inches for high-load situations, and 24 inches for some non-load-bearing partitions and roof trusses. Sheet goods (4-foot-wide plywood and drywall) are designed to land their edges on framing at both 16 and 24-inch OC.
Why It Matters
When you hang something heavy on a wall, you need to hit a stud. Knowing the OC spacing tells you where the next stud is after you find one. At 16-inch OC, studs land at 16, 32, 48, 64, 80, and 96 inches from the corner. A stud finder confirms, but knowing the pattern narrows the search.