A tube cutter includes a first clamp handle, a second clamp handle, a blade, and a holder. The first clamp handle includes an opening. The second clamp handle is pivotally connected with the first clamp handle. The blade is connected with the second clamp handle. The holder includes a first recess and at least one second recess, and the first recess has a width wider than that of the at least one second recess. The holder is movably connected with the first clamp handle to form a first state or a second state with respect to the first clamp handle. The first recess is located at the opening when in the first state and the second recess is located at the opening when in the second state.