This study is aimed to investigate the types of knot failure (untying or breaking) and the tension required to break different suture diameters. A total of 150 knots were fabricated using polyamide sutures with diameters of 6/0, 7/0, and 8/0. The studied knots were either squared or slipped with different numbers of throws (2, 3, 4, 5, and 6), and the following data were recorded: type of failure (untied or broken), number of throws, the tension required to untie or break each knot, slippage, and elongation of the knot. The knots were created in a standardized way with a device and weights, then subjected to a controlled tension. The knots that became untied were: 1=1, 1×1, 2=1, and 2×1, whereas the remaining knots broke. Notably, at least three throws were required to prevent untying, but separately, as in 1=1=1 or 1×1×1. The mean tension needed to break the knots in 6/0, 7/0, and 8/0 sutures were 3.1, 1.3, and 0.6 N, respectively (P < .05), and they were independent of the knot type. The results from this study demonstrate that the knots with geometries of 2=2/2×2 and 1=1=1/1×1×1 were secure, and having additional throws does not increase their security. Further, tensile strength reduces with decreased suture size.