Both thin and thick trimmer line have their uses, but depending on what you’re trying to cut, one will be better suited than the other. Thin trimmer line is better for light-duty work, like small yards that are only cutting away grass and weeds. Thick trimmer lines are better at managing large areas with dense weeds, thick brush, or overgrown grass. Generally, thick trimmers have more cutting power while thin trimmers put less strain on the trimmer’s motor.