Example: Light Welterweight fighter at 140lbs and a Welterweight at 144lbs fight.
The IKF looks for the most narrow weight spread, which is always in the lower weight class of the two. For Light Welterweight, the weight spread is 5lbs, whereas in the Welterweight class it’s 7lbs, it goes to a 5 lb. spread. A fight can only happen inside the limits of the weight class for the lightest fighter. For this example, (Light Welterweight at 140lbs and a Welterweight at 144lbs) this would be OK as a catch weight. If the Light Welterweight fighter was 138lbs and the Welterweight at 144lbs, that 6lb differential would not be allowed.
If you require more detail, please contact the Promoter.