F=ma and w=mg; with acceleration = gravity, then Force = weight. lb is a mass lbf is a force kg is a mass I would then assume that kgf is a force. But the units of force in SI units is Newton. So I would conclude that 1 kgf = 1 N. But it does not... When somebody says that something weighs 1 lb, then dividing by 32.2 ft/sec2 will define the mass in units of slug or lbm. When somebody says that something weighs 1 kg, they are not saying that it weighs 1 kg, but has 1 kg of mass, because if you multiply by 9.81 m/sec2, you get the units of Newton. I have gotten thoroughly confused on this. Please help.