Follow the direction of the pull

Imagine a standing curl with a band under your feet. The band stretches as your hands rise. With a dumbbell, the external load stays the same, but the turning effect around your elbow depends on the forearm's position. Neither exercise provides an identical challenge throughout the repetition.

A band labeled with a resistance range is therefore not interchangeable with a dumbbell of one listed weight. The starting length and amount of stretch matter.

Make a band exercise repeatable

An intact band and an anchor intended for the task matter more than the color printed on a training plan. Inspect the equipment and follow its attachment instructions; a slipping anchor changes the exercise abruptly.

The practical question is whether the setup offers a useful, controllable challenge through your intended movement. If a band substitution feels dramatically harder at one end, that may reflect the resistance pattern rather than a sudden difference in your strength.