This is a big question because of the wide variance of individual strength levels. Fortunately a 41 Inch standard size Quantum Band provides a resistance variability of at least 30 lbs regardless which band you choose. For example a black medium band will create a resistance between 30 to 60 lbs depending on the starting tension and end of movement tension. Comparing this to a constant free weight resistance that has only 1 resistance level a band provides the user with multiple levels of resistance in a single band. That said, we still recommend purchasing at least 2 or 3 band levels of resistance but that is a whole lot less expensive and more space efficient than having to purchase a dozen pairs of dumbbells.